Showing papers on "Integrase published in 2012"
TL;DR: Recent advances in HIV-1 structural biology are reviewed, focusing on the molecular mechanisms of viral replication and on the development of new therapeutics.
Abstract: Three-dimensional molecular structures can provide detailed information on biological mechanisms and, for cases in which the molecular function affects human health, can significantly aid in the development of therapeutic interventions. For almost 25 years, key components of the lentivirus HIV-1, including the envelope glycoproteins, the capsid and the replication enzymes reverse transcriptase, integrase and protease, have been scrutinized to near atomic-scale resolution. Moreover, structural analyses of the interactions between viral and host cell components have yielded key insights into the mechanisms of viral entry, chromosomal integration, transcription and egress from cells. Here, we review recent advances in HIV-1 structural biology, focusing on the molecular mechanisms of viral replication and on the development of new therapeutics.
362 citations
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TL;DR: The chemistry of the IN-mediated DNA breaking and joining steps is well worked out, and structures of IN-DNA complexes have now clarified how the overall complex assembles, and models for some of the molecular mechanisms involved have been proposed.
Abstract: Retroviruses are distinguished from other viruses by two characteristic steps in the viral replication cycle. The first is reverse transcription, which results in the production of a double-stranded DNA copy of the viral RNA genome, and the second is integration, which results in covalent attachment of the DNA copy to host cell DNA. The initial catalytic steps of the integration reaction are performed by the virus-encoded integrase (IN) protein. The chemistry of the IN-mediated DNA breaking and joining steps is well worked out, and structures of IN-DNA complexes have now clarified how the overall complex assembles. Methods developed during these studies were adapted for identification of IN inhibitors, which received FDA approval for use in patients in 2007. At the chromosomal level, HIV integration is strongly favored in active transcription units, which may promote efficient viral gene expression after integration. HIV IN binds to the cellular factor LEDGF/p75, which promotes efficient infection and tethers IN to favored target sites. The HIV integration machinery must also interact with many additional host factors during infection, including nuclear trafficking and pore proteins during nuclear entry, histones during initial target capture, and DNA repair proteins during completion of the DNA joining steps. Models for some of the molecular mechanisms involved have been proposed, but important details remain to be clarified.
311 citations
TL;DR: In vitro selection experiments with DTG using viruses of subtypes B, C, and A/G and showed that the most common mutation to emerge was R263K, which does confer low-level resistance to DTG and decreased integration in cell culture without altering reverse transcription.
Abstract: Integrase (IN) strand transfer inhibitors (INSTIs) have been developed to inhibit the ability of HIV-1 integrase to irreversibly link the reverse-transcribed viral DNA to the host genome. INSTIs have proven their high efficiency in inhibiting viral replication in vitro and in patients. However, first-generation INSTIs have only a modest genetic barrier to resistance, allowing the virus to escape these powerful drugs through several resistance pathways. Second-generation INSTIs, such as dolutegravir (DTG, S/GSK1349572), have been reported to have a higher resistance barrier, and no novel drug resistance mutation has yet been described for this drug. Therefore, we performed in vitro selection experiments with DTG using viruses of subtypes B, C, and A/G and showed that the most common mutation to emerge was R263K. Further analysis by site-directed mutagenesis showed that R263K does confer low-level resistance to DTG and decreased integration in cell culture without altering reverse transcription. Biochemical cell-free assays performed with purified IN enzyme containing R263K confirmed the absence of major resistance against DTG and showed a slight decrease in 3' processing and strand transfer activities compared to the wild type. Structural modeling suggested and in vitro IN-DNA binding assays show that the R263K mutation affects IN-DNA interactions.
214 citations
TL;DR: 2-(quinolin-3-yl) acetic acid derivatives impairs both integrase-LEDGF binding and LEDGF-independent integrase catalytic activities with similar IC50 values, defining them as bona fide allosteric inhibitors of integrase function.
169 citations
TL;DR: It is shown that in addition to the properties already known for LEDGINs, the binding of tBPQAs to the IN dimer interface inhibits IN enzymatic activity in a LEDGF-independent manner, and this inhibition occurs at or prior to the viral DNA 3′-processing step.
162 citations
TL;DR: Detailed mechanism-of-action studies reveal that the allosteric mode of inhibition is likely caused by an effect on HIV-1 integrase oligomerization, and cross-resistance profiling proves the distinct mode of action of LEDGINs and INSTIs.
Abstract: Targeting the HIV integrase (HIV IN) is a clinically validated approach for designing novel anti-HIV therapies. We have previously described the discovery of a novel class of integration inhibitors, 2-(quinolin-3-yl)acetic acid derivatives, blocking HIV replication at a low micromolar concentration through binding in the LEDGF/p75 binding pocket of HIV integrase, hence referred to as LEDGINs. Here we report the detailed characterization of their mode of action. The design of novel and more potent analogues with nanomolar activity enabled full virological evaluation and a profound mechanistic study. As allosteric inhibitors, LEDGINs bind to the LEDGF/p75 binding pocket in integrase, thereby blocking the interaction with LEDGF/p75 and interfering indirectly with the catalytic activity of integrase. Detailed mechanism-of-action studies reveal that the allosteric mode of inhibition is likely caused by an effect on HIV-1 integrase oligomerization. The multimodal inhibition by LEDGINs results in a block in HIV integration and in a replication deficiency of progeny virus. The allosteric nature of LEDGINs leads to synergy in combination with the clinically approved active site HIV IN strand transfer inhibitor (INSTI) raltegravir, and cross-resistance profiling proves the distinct mode of action of LEDGINs and INSTIs. The allosteric nature of inhibition and compatibility with INSTIs underline an interest in further (clinical) development of LEDGINs.
160 citations
TL;DR: HIV-1 has been the target of intensive research at the molecular and biochemical levels for >25 years, which has led to a detailed understanding of viral replication and the development of 24 approved drugs that have five different targets on various viral proteins and one cellular target.
133 citations
TL;DR: A crystal structure of prototype foamy virus IN bound to viral DNA prior to 3′‐processing is reported and a striking substrate mimicry utilized by the inhibitors in their binding to the IN active site is highlighted.
Abstract: Retroviral integrase (IN) is responsible for two consecutive reactions, which lead to insertion of a viral DNA copy into a host cell chromosome. Initially, the enzyme removes di- or trinucleotides from viral DNA ends to expose 3′-hydroxyls attached to the invariant CA dinucleotides (3′-processing reaction). Second, it inserts the processed 3′-viral DNA ends into host chromosomal DNA (strand transfer). Herein, we report a crystal structure of prototype foamy virus IN bound to viral DNA prior to 3′-processing. Furthermore, taking advantage of its dependence on divalent metal ion cofactors, we were able to freeze trap the viral enzyme in its ground states containing all the components necessary for 3′-processing or strand transfer. Our results shed light on the mechanics of retroviral DNA integration and explain why HIV IN strand transfer inhibitors are ineffective against the 3′-processing step of integration. The ground state structures moreover highlight a striking substrate mimicry utilized by the inhibitors in their binding to the IN active site and suggest ways to improve upon this clinically relevant class of small molecules.
130 citations
TL;DR: The generation of a human somatic LEDGF/p75 knockout cell line is reported that allows the study of spreading HIV-1 infection in the absence of LEDsGF/ p75, and results further support the potential of LEDGINs as allosteric integrase inhibitors.
Abstract: Lens epithelium–derived growth factor (LEDGF/p75) is a cellular cofactor of HIV-1 integrase (IN) that interacts with IN through its IN binding domain (IBD) and tethers the viral pre-integration complex to the host cell chromatin. Here we report the generation of a human somatic LEDGF/p75 knockout cell line that allows the study of spreading HIV-1 infection in the absence of LEDGF/p75. By homologous recombination the exons encoding the LEDGF/p75 IBD (exons 11 to 14) were knocked out. In the absence of LEDGF/p75 replication of laboratory HIV-1 strains was severely delayed while clinical HIV-1 isolates were replication-defective. The residual replication was predominantly mediated by the Hepatoma-derived growth factor related protein 2 (HRP-2), the only cellular protein besides LEDGF/p75 that contains an IBD. Importantly, the recently described IN-LEDGF/p75 inhibitors (LEDGINs) remained active even in the absence of LEDGF/p75 by blocking the interaction with the IBD of HRP-2. These results further support the potential of LEDGINs as allosteric integrase inhibitors.
122 citations
TL;DR: Recent advances in knowledge of HIV-1 DNA integration are reviewed, including small molecules that bind at the host factor lens epithelium-derived growth factor/p75-binding site on HIV- 1 integrase promote dimerization and inhibit integrase-viral DNA assembly and catalysis.
107 citations
TL;DR: The first in vivo evidence of the impact of SOS response activated by the antibiotic treatment given to a patient and its output in terms of resistance development is reported, demonstrating that in human hosts, the antibiotic-induced SOS response in pathogens could play a pivotal role in adaptation process of the bacteria.
Abstract: Bacterial resistance to β-lactams may rely on acquired β-lactamases encoded by class 1 integron-borne genes. Rearrangement of integron cassette arrays is mediated by the integrase IntI1. It has been previously established that integrase expression can be activated by the SOS response in vitro, leading to speculation that this is an important clinical mechanism of acquiring resistance. Here we report the first in vivo evidence of the impact of SOS response activated by the antibiotic treatment given to a patient and its output in terms of resistance development. We identified a new mechanism of modulation of antibiotic resistance in integrons, based on the insertion of a genetic element, the gcuF1 cassette, upstream of the integron-borne cassette blaOXA-28 encoding an extended spectrum β-lactamase. This insertion creates the fused protein GCUF1-OXA-28 and modulates the transcription, the translation, and the secretion of the β-lactamase in a Pseudomonas aeruginosa isolate (S-Pae) susceptible to the third generation cephalosporin ceftazidime. We found that the metronidazole, not an anti-pseudomonal antibiotic given to the first patient infected with S-Pae, triggered the SOS response that subsequently activated the integrase IntI1 expression. This resulted in the rearrangement of the integron gene cassette array, through excision of the gcuF1 cassette, and the full expression the β-lactamase in an isolate (R-Pae) highly resistant to ceftazidime, which further spread to other patients within our hospital. Our results demonstrate that in human hosts, the antibiotic-induced SOS response in pathogens could play a pivotal role in adaptation process of the bacteria.
TL;DR: Findings help to rule out the host factor-IN interactions as the primary antiviral targets of LEDGF/p75-binding site IN inhibitors and suggest that IN and/or other host factors contribute to integration specificity in the absence of LEDsGF/ p75 and HRP2.
Abstract: The binding of integrase (IN) to lens epitheliumderived growth factor (LEDGF)/p75 in large part determines the efficiency and specificity of HIV-1 integration. However, a significant residual preference for integration into active genes persists in Psip1 (the gene that encodes for LEDGF/p75) knockout (KO) cells. One other cellular protein, HRP2, harbors both the PWWP and IN-binding domains that are important for LEDGF/p75 co-factor function. To assess the role of HRP2 in HIV-1 integration, cells generated from Hdgfrp2 (the gene that encodes for HRP2) and Psip1/ Hdgfrp2 KO mice were infected alongside matched control cells. HRP2 depleted cells supported normal infection, while disruption of Hdgfrp2 in Psip1 KO cells yielded additional defects in the efficiency and specificity of integration. These deficits were largely restored by ectopic expression of either LEDGF/p75 or HRP2. The double-KO cells nevertheless supported residual integration into genes, indicating that IN and/or other host factors contribute to integration specificity in the absence of LEDGF/p75 and HRP2. Psip1 KO significantly increased the potency of an allosteric inhibitor that binds the LEDGF/p75 binding site on IN, a result that was not significantly altered by Hdgfrp2 disruption. These findings help to rule out the host factor-IN interactions as the primary antiviral targets of LEDGF/p75-binding site IN inhibitors.
TL;DR: Because of the susceptibility to drug resistance, INSTIs should always be used together with other effective ARV drugs and that high-level adherence to treatment be maintained.
Abstract: Purpose of review Integrase strand transfer inhibitors (INSTIs) have become a key component of antiretroviral therapy since the approval of twice-daily raltegravir in 2007 and the more recent approval of elvitegravir in 2012. At the same time, a third compound, dolutegravir, is in late-phase clinical trials, being tested as part of a multidrug once-daily formulation comprising this INSTI and two other antiretroviral (ARV) drugs. This review focuses on the factors leading to the development of drug resistance mutations (DRMs) against INSTIs, evidence of cross-resistance among them, and the results of regimen simplification in regard to this topic. Recent findings Sequencing data show that DRMs are highly dynamic in patients failing INSTI therapy. Considerations of viral fitness and drug resistance can together determine the evolution of drug resistance mutations, and in this regard the Y143 and Q148 pathways are superior to the N155 pathway in the promotion of resistance. Preventing the emergence of DRMs requires that effective reverse transcriptase or other inhibitors be used together with INSTIs and that high-level adherence to treatment be maintained. Summary Because of the susceptibility to drug resistance, INSTIs should always be used together with other effective ARV drugs.
TL;DR: It is shown that transformation, another horizontal gene transfer (HGT) mechanism, also triggers integrase expression through SOS induction, underlining the importance of HGT in genome plasticity and a new cyclic AMP-cAMP receptor protein (CRP)-dependent regulation mechanism of the integrase.
Abstract: The human pathogen Vibrio cholerae carries a chromosomal superintegron (SI). The SI contains an array of hundreds of gene cassettes organized in tandem which are stable under conditions when no particular stress is applied to bacteria (such as during laboratory growth). Rearrangements of these cassettes are catalyzed by the activity of the associated integron integrase. Understanding the regulation of integrase expression is pivotal to fully comprehending the role played by this genetic reservoir for bacterial adaptation and its connection with the development of antibiotic resistance. Our previous work established that the integrase is regulated by the bacterial SOS response and that it is induced during bacterial conjugation. Here, we show that transformation, another horizontal gene transfer (HGT) mechanism, also triggers integrase expression through SOS induction, underlining the importance of HGT in genome plasticity. Moreover, we report a new cyclic AMP (cAMP)-cAMP receptor protein (CRP)-dependent regulation mechanism of the integrase, highlighting the influence of the extracellular environment on chromosomal gene content. Altogether, our data suggest an interplay between different stress responses and regulatory pathways for the modulation of the recombinase expression, thus showing how the SI remodeling mechanism is merged into bacterial physiology.
TL;DR: The history of the clinical development of HIV integrase inhibitors, the development of antiviral drug resistance and the need for new antiviral compounds are considered.
Abstract: Integration of the viral genome into host cell chromatin is a pivotal and unique step in the replication cycle of retroviruses, including HIV. Inhibiting HIV replication by specifically blocking the viral integrase enzyme that mediates this step is an obvious and attractive therapeutic strategy. After concerted efforts, the first viable integrase inhibitors were developed in the early 2000s, ultimately leading to the clinical licensure of the first integrase strand transfer inhibitor, raltegravir. Similarly structured compounds and derivative second generation integrase strand transfer inhibitors, such as elvitegravir and dolutegravir, are now in various stages of clinical development. Furthermore, other mechanisms aimed at the inhibition of viral integration are being explored in numerous preclinical studies, which include inhibition of 3' processing and chromatin targeting. The development of new clinically useful compounds will be aided by the characterization of the retroviral intasome crystal structure. This review considers the history of the clinical development of HIV integrase inhibitors, the development of antiviral drug resistance and the need for new antiviral compounds.
TL;DR: This chapter focuses on genome-wide applications of transposons, Flp recombinase, and ΦC31 integrase that greatly facilitate experimental manipulation of Drosophila.
Abstract: Transposable elements, the Flp recombinase, and the ΦC31 integrase are used in Drosophila melanogaster for numerous genome-wide manipulations. Often, their use is combined in a synergistic fashion to alter and engineer the fruit fly genome. Transposons are the foundation for all transgenic technologies in flies and hence almost all innovations in the fruit fly. They have been instrumental in the generation of genome-wide collections of insertions for gene disruption and manipulation. Many important transgenic strains of these collections are available from public repositories. The Flp protein is the most widely used recombinase to induce mitotic clones to study individual gene function. However, Flp has also been used to generate chromosome- and genome-wide collections of precise deletions, inversions, and duplications. Similarly, transposons that contain attP attachment sites for the ΦC31 integrase can be used for numerous applications. This integrase was incorporated into a transgenesis system that allows the integration of small to very large DNA fragments that can be easily manipulated through recombineering. This system allowed the creation of genomic DNA libraries for genome-wide gene manipulations and X chromosome duplications. Moreover, the attP sites are being used to create libraries of tens of thousands of RNAi constructs and tissue-specific GAL4 lines. This chapter focuses on genome-wide applications of transposons, Flp recombinase, and ΦC31 integrase that greatly facilitate experimental manipulation of Drosophila.
TL;DR: Integrase inhibitors provide a potent option for the treatment of HIV infection, and drug resistance remains a challenge, which may be partially overcome by the introduction of second-generation compounds.
Abstract: Purpose of reviewThis review highlights recent data on the pathways of resistance that impact the clinical activity of first-generation and second-generation integrase inhibitors.Recent findingsRaltegravir (RAL) and elvitegravir (EVG) are highly efficacious in first-line antiretroviral therapy, with
TL;DR: In vitro studies demonstrate that the resistance profile of the M1 and M4 metabolites of elvitegravir overlaps with that of the parent molecule elvitescens; as such, their presence at low levels is not considered clinically relevant.
TL;DR: The biochemical mechanism of integration, which is now quite well understood, is discussed, and recent progress towards obtaining atomic-resolution structures of HIV intasomes in complex with inhibitors is discussed.
Abstract: Integration of viral DNA into cellular DNA is an essential step in the replication cycle of HIV and other retroviruses. The first antiviral drugs that target integrase, the viral enzyme that catalyzes DNA integration, have recently been approved and more are in the pipeline. These drugs bind to an intermediate in DNA integration called the intasome, in which a pair of viral DNA ends are synapsed by a tetramer of integrase, rather than free integrase enzyme. We discuss the biochemical mechanism of integration, which is now quite well understood, and recent progress towards obtaining atomic-resolution structures of HIV intasomes in complex with inhibitors. Such structures are ultimately required to understand the detailed mechanism of inhibition and the mechanisms by which mutations in integrase confer resistance. The path from early biochemical studies to therapeutic inhibitors of integrase highlights the value of basic science in fighting human diseases.
TL;DR: Dolutegravir (DTG), a second-generation INI currently in the late stage of clinical development, is an effective orally available drug with a long half-life that does not need to be pharmacologically enhanced, and is effective as a once daily drug in the absence of INi resistance mutations and twice daily in presence of INI resistance mutations.
Abstract: Introduction: Development of new antiretroviral drugs which are highly potent, tolerable over the long term and with a high genetic barrier to resistance is essential for the treatment of a chronic viral disease that requires life-long therapy with near-perfect medication adherence. Integrase inhibitors (INI) are a new class of antiretroviral drugs that block the action of HIV integrase, which catalyses several key steps in the virus life cycle which are essential for insertion of the viral genome into the DNA of host cell. Areas covered: Dolutegravir (DTG), a second-generation INI currently in the late stage of clinical development, is an effective orally available drug with a long half-life that does not need to be pharmacologically enhanced, is effective as a once daily drug in the absence of INI resistance mutations and twice daily in presence of INI resistance mutations. Expert Opinion: DTG, as other drugs in the INI class, appears safe and well tolerated. Results from ongoing large Phase III studies...
TL;DR: The design, chemical synthesis, replicon and biochemical assays, and molecular docking of C-6 or C-7 aryl substituted 2-hydroxyisoquinoline-1,3-diones as novel HCV inhibitors are described and it is suggested that these inhibitors may bind to the NS5B active site.
TL;DR: It is demonstrated that HRP-2 overexpression can compensate for the absence of LEDGF/p75 and indicate that the residual bias in integration targeting observed in the absence and in the presence of LEDsGF/ p75 can be ascribed to HRp-2.
Abstract: Background: Lens epithelium–derived growth factor (LEDGF/p75) is a cellular co-factor of HIV-1 integrase (IN) that tethers the viral pre-integration complex to the host cell chromatin and determines the genome wide integration site distribution pattern of HIV-1. Recently, we demonstrated that HIV-1 replication was reduced in LEDGF/p75 knockout (KO) cells. LEDGF/p75 KO significantly altered the integration site preference of HIV-1, but the pattern remained distinct from a computationally generated matched random control set (MRC), suggesting the presence of an alternative tethering factor. We previously identified Hepatoma-derived growth factor related protein 2 (HRP-2) as a factor mediating LEDGF/p75-independent HIV-1 replication. However, the role of HRP-2 in HIV-1 integration site selection was not addressed. Findings: We studied the HIV-1 integration site distribution in the presence and absence of LEDGF/p75 and/or HRP-2, and in LEDGF/p75-depleted cells that overexpress HRP-2. We show that HRP-2 functions as a co-factor of HIV-1 IN in LEDGF/p75-depleted cells. Endogenous HRP-2 only weakly supported HIV-1 replication in LEDGF/p75 depleted cells. However, HRP-2 overexpression rescued HIV-1 replication and restored integration in RefSeq genes to wild-type levels. Additional HRP-2 KD in LEDGF/p75-depleted cells reduces integration frequency in transcription units and shifts the integration distribution towards random. Conclusions: We demonstrate that HRP-2 overexpression can compensate for the absence of LEDGF/p75 and indicate that the residual bias in integration targeting observed in the absence of LEDGF/p75 can be ascribed to HRP-2. Knockdown of HRP-2 upon LEDGF/p75 depletion results in a more random HIV-1 integration pattern. These data therefore reinforce the understanding that LEDGF/p75 is the dominant HIV-1 IN co-factor.
TL;DR: Several newly identified resistance mutations, such as G118R, R263K and S153Y, have been identified through tissue culture selection studies with second-generation integrase strand-transfer inhibitors (INSTIs), which add to the understanding of the three previously identified resistance pathways involving mutations at positions Y143, N155 and Q148.
TL;DR: In this study, pathways of resistance at failure were not predicted by baseline mutations, suggesting that evolution plus stochastic selection plays a major role in the appearance of integrase-resistance mutations, whereas fitness and resistance are dominant factors acting for the late selection of resistant quasispecies.
Abstract: Background. The dynamics of raltegravir-resistant variants and their impact on virologic response in 23 HIV-1‐ infected patients, who started a salvage raltegravir-containing regimen, were investigated. Methods. Integrase population sequencing and Ultra-Deep-454 Pyrosequencing (UDPS) were performed on plasma samples at baseline and at raltegravir failure. All integrase mutations detected at a frequency $1% were considered to be reliable for the UDPS analyses. Phylogenetic and phenotypic resistance analyses were also performed. Results. At baseline, primary resistance mutations were not detected by both population and UDPS genotypic assays; few secondary mutations (T97A-V151I-G163R) were rarely detected and did not show any statistically association either with virologic response at 24-weeks or with the development of resistant variants at failure. At UDPS, not all resistant variants appearing early during treatment evolved as major populations during failure; only specific resistance pathways (Y143R-Q148H/R-N155H) associated with an increased rate of fitness and phenotypic resistance were selected. Conclusions. Resistance to raltegravir in integrase strand transfer inhibitor‐naive patients remains today a rare event, which might be changed by future extensive use of such drugs. In our study, pathways of resistance at failure were not predicted by baseline mutations, suggesting that evolution plus stochastic selection plays a major role in the appearance of integrase-resistance mutations, whereas fitness and resistance are dominant factors acting for the late selection of resistant quasispecies.
TL;DR: Recent mutations selected in vitro with second-generation INSTIs suggest the existence of low levels of cross-resistance between these drugs and first-generation compounds, and the emergence of mutations at position Q148 should be monitored whenever possible.
Abstract: Purpose of reviewHIV integrase inhibitors are potent antiretroviral drugs that efficiently decrease viral load in patients. Emergence of resistance mutations against this new class of drugs represents a threat to their long-term efficacy. The purpose of this review is to provide new information abou
TL;DR: Integrase inhibitors are characterized by a more rapid decrease in viral load in HIV-1-infected patients initiating therapy and possess prolonged window for intervention in the viral life cycle, thus offering an advantage in the setting of HIV- 1 chemoprevention.
Abstract: Purpose of reviewIntegrase strand transfer inhibitors are the most recent class of antiretroviral agents to be introduced into clinical practice. This review describes the discovery of the first inhibitors and insights into their distinct mechanism of action with potential translational implications
TL;DR: Biophysical analyses including circular dichroism, analytical ultracentrifugation, small-angle x-ray scattering, and homology modeling provide insight into TNPO3 architecture and indicate that it is highly structured and exists in a monomer-dimer equilibrium in solution.
TL;DR: This review focuses on the magnesium metal cofactors and on their catalytic and biological properties, as well as on the structural features of the most relevant metal chelating compounds developed as antiviral agents against some of themost important viral targets.
TL;DR: This work provides proof-of-concept for direct targeting of LEDGF/p75 as novel therapeutic strategy and the CPs thereby serve as scaffold for future development of new HIV therapeutics.
TL;DR: By isolating and examining the role of the MBG in a series of INSTIs, a scaffold is identified that may provide access to a unique class of HIV-1 IN inhibitors, and may help overcome rising raltegravir resistance.
Abstract: A series of HIV integrase (HIV-1 IN) inhibitors were synthesized to evaluate the role of the metal-binding group (MBG) in this class of metalloenzyme inhibitors. A total of 21 different raltegravir-chelator derivative (RCD) compounds were prepared that differed only in the nature of the MBG. These IN strand-transfer inhibitors (INSTIs) were evaluated in vitro in cell-free enzyme activity assays, and the in vitro results were further validated in cell culture experiments. All of the active compounds showed selective inhibition of the strand-transfer reaction over 3′-processing, suggesting a common mode of action with raltegravir. The results of the in vitro activity suggest that the nature of the MBG donor atoms, the overall MBG structure, and the specific arrangement of the MBG donor atom triad are essential for obtaining maximal HIV-1 IN inhibition. At least two compounds (RCD-4, RCD-5) containing a hydroxypyrone MBG were found to display superior strand-transfer inhibition when compared to an abbreviated analogue of raltegravir (RCD-1). By isolating and examining the role of the MBG in a series of INSTIs, we have identified a scaffold (hydroxypyrones) that may provide access to a unique class of HIV-1 IN inhibitors, and may help overcome rising raltegravir resistance.