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Journal ArticleDOI

Site-specific C-terminal and internal loop labeling of proteins using sortase-mediated reactions

01 Sep 2013-Nature Protocols (Nature Publishing Group)-Vol. 8, Iss: 9, pp 1787-1799
TL;DR: In this paper, the authors describe the expression and purification conditions for two sortase A enzymes that have different recognition sequences and provide a protocol that allows the functionalization of any given protein at its C terminus, or, for select proteins, at an internal site.
Abstract: Methods for site-specific modification of proteins should be quantitative and versatile with respect to the nature and size of the biological or chemical targets involved. They should require minimal modification of the target, and the underlying reactions should be completed in a reasonable amount of time under physiological conditions. Sortase-mediated transpeptidation reactions meet these criteria and are compatible with other labeling methods. Here we describe the expression and purification conditions for two sortase A enzymes that have different recognition sequences. We also provide a protocol that allows the functionalization of any given protein at its C terminus, or, for select proteins, at an internal site. The target protein is engineered with a sortase-recognition motif (LPXTG) at the place where modification is desired. Upon recognition, sortase cleaves the protein between the threonine and glycine residues, facilitating the attachment of an exogenously added oligoglycine peptide modified with the functional group of choice (e.g., fluorophore, biotin, protein or lipid). Expression and purification of sortase takes ∼3 d, and sortase-mediated reactions take only a few minutes, but reaction times can be extended to increase yields.

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Citations
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Journal ArticleDOI
TL;DR: Radical Polymerization and Copper(0) Mediated polymerization): From Fundamentals to Bioapplications
Abstract: Radical Polymerization and Copper(0) Mediated Polymerization): From Fundamentals to Bioapplications Cyrille Boyer,*,†,‡ Nathaniel Alan Corrigan,‡ Kenward Jung,‡ Diep Nguyen,‡ Thuy-Khanh Nguyen,‡ Nik Nik M. Adnan,†,‡ Susan Oliver,†,‡ Sivaprakash Shanmugam,‡ and Jonathan Yeow†,‡ †Australian Centre for Nanomedicine, and ‡Centre for Advanced Macromolecular Design (CAMD), School of Chemical Engineering, University of New South Wales, Sydney 2052, Australia

389 citations

Journal ArticleDOI
23 Oct 2015-Science
TL;DR: It is found that the PrgJ-NAIP2-NLRC4 inflammasome is assembled into multisubunit disk-like structures through a unidirectional adenosine triphosphatase polymerization, primed with a single PrGJ-activated NAIP2 per disk.
Abstract: The NLR family apoptosis inhibitory proteins (NAIPs) bind conserved bacterial ligands, such as the bacterial rod protein PrgJ, and recruit NLR family CARD-containing protein 4 (NLRC4) as the inflammasome adapter to activate innate immunity. We found that the PrgJ-NAIP2-NLRC4 inflammasome is assembled into multisubunit disk-like structures through a unidirectional adenosine triphosphatase polymerization, primed with a single PrgJ-activated NAIP2 per disk. Cryo–electron microscopy (cryo-EM) reconstruction at subnanometer resolution revealed a ~90° hinge rotation accompanying NLRC4 activation. Unlike in the related heptameric Apaf-1 apoptosome, in which each subunit needs to be conformationally activated by its ligand before assembly, a single PrgJ-activated NAIP2 initiates NLRC4 polymerization in a domino-like reaction to promote the disk assembly. These insights reveal the mechanism of signal amplification in NAIP-NLRC4 inflammasomes.

327 citations

Journal ArticleDOI
TL;DR: How Nbs are being explored as therapeutics in many fields of medicine, including oncology, inflammatory, infectious and neurological diseases, and imaging, is discussed and their potential for use in the diagnosis and monitoring of diseases is highlighted.

314 citations

Journal ArticleDOI
12 Jan 2021-Science
TL;DR: In this paper, the authors used x-ray crystallography and cryo-electron microscopy to define two distinct binding epitopes of the SARS-CoV-2 spike protein.
Abstract: The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread, with devastating consequences. For passive immunization efforts, nanobodies have size and cost advantages over conventional antibodies. In this study, we generated four neutralizing nanobodies that target the receptor binding domain of the SARS-CoV-2 spike protein. We used x-ray crystallography and cryo-electron microscopy to define two distinct binding epitopes. On the basis of these structures, we engineered multivalent nanobodies with more than 100 times the neutralizing activity of monovalent nanobodies. Biparatopic nanobody fusions suppressed the emergence of escape mutants. Several nanobody constructs neutralized through receptor binding competition, whereas other monovalent and biparatopic nanobodies triggered aberrant activation of the spike fusion machinery. These premature conformational changes in the spike protein forestalled productive fusion and rendered the virions noninfectious.

247 citations

Journal ArticleDOI
TL;DR: This Perspective provides an overview of N-terminal modification techniques and the chemical rationale governing each, along with their uses in a number of diverse biological applications.
Abstract: The formation of well-defined protein bioconjugates is critical for many studies and technologies in chemical biology. Tried-and-true methods for accomplishing this typically involve the targeting of cysteine residues, but the rapid growth of contemporary bioconjugate applications has required an expanded repertoire of modification techniques. One very powerful set of strategies involves the modification of proteins at their N termini, as these positions are typically solvent exposed and provide chemically distinct sites for many protein targets. Several chemical techniques can be used to modify N-terminal amino acids directly or convert them into unique functional groups for further ligations. A growing number of N-terminus-specific enzymatic ligation strategies have provided additional possibilities. This Perspective provides an overview of N-terminal modification techniques and the chemical rationale governing each. Examples of specific N-terminal protein conjugates are provided, along with their uses in a number of diverse biological applications.

238 citations

References
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Journal ArticleDOI
TL;DR: The utility of this modular protein tagging system for cellular imaging and protein immobilization is demonstrated by analyzing multiple molecular processes associated with NF-kappaB-mediated cellular physiology, including imaging of subcellular protein translocation and capture of protein--protein and protein--DNA complexes.
Abstract: We have designed a modular protein tagging system that allows different functionalities to be linked onto a single genetic fusion, either in solution, in living cells, or in chemically fixed cells. The protein tag (HaloTag) is a modified haloalkane dehalogenase designed to covalently bind to synthetic ligands (HaloTag ligands). The synthetic ligands comprise a chloroalkane linker attached to a variety of useful molecules, such as fluorescent dyes, affinity handles, or solid surfaces. Covalent bond formation between the protein tag and the chloroalkane linker is highly specific, occurs rapidly under physiological conditions, and is essentially irreversible. We demonstrate the utility of this system for cellular imaging and protein immobilization by analyzing multiple molecular processes associated with NF-κB-mediated cellular physiology, including imaging of subcellular protein translocation and capture of protein−protein and protein−DNA complexes.

1,822 citations

Journal ArticleDOI
TL;DR: A general method for the covalent labeling of fusion proteins in vivo that complements existing methods for noncovalentlabeling of proteins and that may open up new ways of studying proteins in living cells is described.
Abstract: Characterizing the movement, interactions, and chemical microenvironment of a protein inside the living cell is crucial to a detailed understanding of its function. Most strategies aimed at realizing this objective are based on genetically fusing the protein of interest to a reporter protein that monitors changes in the environment of the coupled protein. Examples include fusions with fluorescent proteins, the yeast two-hybrid system, and split ubiquitin. However, these techniques have various limitations, and considerable effort is being devoted to specific labeling of proteins in vivo with small synthetic molecules capable of probing and modulating their function. These approaches are currently based on the noncovalent binding of a small molecule to a protein, the formation of stable complexes between biarsenical compounds and peptides containing cysteines, or the use of biotin acceptor domains. Here we describe a general method for the covalent labeling of fusion proteins in vivo that complements existing methods for noncovalent labeling of proteins and that may open up new ways of studying proteins in living cells.

1,702 citations

Journal ArticleDOI
30 Jul 1999-Science
TL;DR: The protein specified by srtA, sortase, may be a useful target for the development of new antimicrobial drugs.
Abstract: Surface proteins of Gram-positive bacteria are linked to the bacterial cell wall by a mechanism that involves cleavage of a conserved Leu-Pro-X-Thr-Gly (LPXTG) motif and that occurs during assembly of the peptidoglycan cell wall A Staphylococcus aureus mutant defective in the anchoring of surface proteins was isolated and shown to carry a mutation in the srtA gene Overexpression of srtA increased the rate of surface protein anchoring, and homologs of srtA were found in other pathogenic Gram-positive bacteria The protein specified by srtA, sortase, may be a useful target for the development of new antimicrobial drugs

975 citations

Journal ArticleDOI
TL;DR: The generation of an AGT-based tag is reported, named CLIP-tag, which reacts specifically with O2-benzylcytosine derivatives, which is derived from the human DNA repair protein O6-alkylguanine-DNA alkyltransferase (AGT).

925 citations