The effect of environmental conditions on expression of Bacteroides fragilis and Bacteroides thetaiotaomicron C10 protease genes
TL;DR: Genes encoding C10 proteases are increasingly identified in operons which also contain genes encoding proteins homologous to protease inhibitors, suggesting they may have distinct roles in the bacterial-host interaction.
Abstract: Bacteroides fragilis and Bacteroides thetaiotaomicron are members of the normal human intestinal microbiota. However, both organisms are capable of causing opportunistic infections, during which the environmental conditions to which the bacteria are exposed change dramatically. To further explore their potential for contributing to infection, we have characterized the expression in B. thetaiotaomicron of four homologues of the gene encoding the C10 cysteine protease SpeB, a potent extracellular virulence factor produced by Streptococcus pyogenes. We identified a paralogous set of genes (btp genes) in the B. thetaiotaomicron genome, that were related to C10 protease genes we recently identified in B. fragilis. Similar to C10 proteases found in B. fragilis, three of the B. thetaiotaomicron homologues were transcriptionally coupled to genes encoding small proteins that are similar in structural architecture to Staphostatins, protease inhibitors associated with Staphopains in Staphylococcus aureus. The expression of genes for these C10 proteases in both B. fragilis and B. thetaiotaomicron was found to be regulated by environmental stimuli, in particular by exposure to oxygen, which may be important for their contribution to the development of opportunistic infections. Genes encoding C10 proteases are increasingly identified in operons which also contain genes encoding proteins homologous to protease inhibitors. The Bacteroides C10 protease gene expression levels are responsive to different environmental stimuli suggesting they may have distinct roles in the bacterial-host interaction.
Citations
More filters
TL;DR: The first whole genome exploration of the Bacteroidales family S24-7 is provided, for which the name “Candidatus Homeothermaceae” is proposed, using 30 population genomes extracted from fecal samples of four different animal hosts.
Abstract: Our view of host-associated microbiota remains incomplete due to the presence of as yet uncultured constituents. The Bacteroidales family S24-7 is a prominent example of one of these groups. Marker gene surveys indicate that members of this family are highly localized to the gastrointestinal tracts of homeothermic animals and are increasingly being recognized as a numerically predominant member of the gut microbiota; however, little is known about the nature of their interactions with the host. Here, we provide the first whole genome exploration of this family, for which we propose the name “Candidatus Homeothermaceae,” using 30 population genomes extracted from fecal samples of four different animal hosts: human, mouse, koala, and guinea pig. We infer the core metabolism of “Ca. Homeothermaceae” to be that of fermentative or nanaerobic bacteria, resembling that of related Bacteroidales families. In addition, we describe three trophic guilds within the family, plant glycan (hemicellulose and pectin), host glycan, and α-glucan, each broadly defined by increased abundance of enzymes involved in the degradation of particular carbohydrates. “Ca. Homeothermaceae” representatives constitute a substantial component of the murine gut microbiota, as well as being present within the human gut, and this study provides important first insights into the nature of their residency. The presence of trophic guilds within the family indicates the potential for niche partitioning and specific roles for each guild in gut health and dysbiosis.
455 citations
Cites background from "The effect of environmental conditi..."
...Homeothermaceae” does not preclude a typically commensal relationship with the host; however, they may provide the capacity for opportunistic infection under the appropriate conditions [75]....
[...]
...thetaiotaomicron [74, 75] and in the periodontal pathogen Prevotella intermedia where the homolog interpain A is involved in the inhibition of the immune response via complement degradation [76]....
[...]
TL;DR: The recent observation of ETBF-bearing biofilms in colon biopsies from humans with colon cancer susceptibility loci strongly suggests that ETBF is a driver of colorectal cancer.
56 citations
TL;DR: A subset of patients with IBS, especially in PI-IBS, has substantially high faecal PA, greater symptoms, impaired barrier and reduced microbial diversity.
Abstract: Objective The intestinal lumen contains several proteases. Our aim was to determine the role of faecal proteases in mediating barrier dysfunction and symptoms in IBS. Design 39 patients with IBS and 25 healthy volunteers completed questionnaires, assessments of in vivo permeability, ex vivo colonic barrier function in Ussing chambers, tight junction (TJ) proteins, ultrastructural morphology and 16 s sequencing of faecal microbiota rRNA. A casein-based assay was used to measure proteolytic activity (PA) in faecal supernatants (FSNs). Colonic barrier function was determined in mice (ex-germ free) humanised with microbial communities associated with different human PA states. Results Patients with IBS had higher faecal PA than healthy volunteers. 8/20 postinfection IBS (PI-IBS) and 3/19 constipation- predominant IBS had high PA (>95th percentile). High-PA patients had more and looser bowel movements, greater symptom severity and higher in vivo and ex vivo colonic permeability. High-PA FSNs increased paracellular permeability, decreased occludin and increased phosphorylated myosin light chain (pMLC) expression. Serine but not cysteine protease inhibitor significantly blocked high-PA FSN effects on barrier. The effects on barrier were diminished by pharmacological or siRNA inhibition of protease activated receptor-2 (PAR-2). Patients with high-PA IBS had lower occludin expression, wider TJs on biopsies and reduced microbial diversity than patients with low PA. Mice humanised with high-PA IBS microbiota had greater in vivo permeability than those with low-PA microbiota. Conclusion A subset of patients with IBS, especially in PI-IBS, has substantially high faecal PA, greater symptoms, impaired barrier and reduced microbial diversity. Commensal microbiota affects luminal PA that can influence host barrier function.
51 citations
TL;DR: The temperate phage, Bacteroides phage BV01, broadly alters its host’s transcriptome, the prominent human gut symbiont Bactroides vulgatus, demonstrating the complexity of phage-bacteria-mammal relationships and emphasize a need to better understand the role of temperates phages in the gut microbiome.
28 citations
Cites methods from "The effect of environmental conditi..."
...No lytic infection was detected using plaque assays (Kropinski et al., 2009) with 10 B. vulgatus isolates (Table S4), the B. vulgatus cured lysogen (DBV01), B. thetaiotaomicron, and 4 B. dorei isolates on four different growth media: tryptone-yeast extract-glucose broth (TYG), brain heart infusion (BHI) agar supplemented with 10% defibrinated horse blood (HB), BHI supplemented with hemin and menadione (BHI-HM) (Thornton et al., 2012), and supplemented TYG (TYGS) (Goodman et al., 2009)....
[...]
...dorei isolates on four different growth media: tryptone-yeast extract-glucose broth (TYG), brain heart infusion (BHI) agar supplemented with 10% defibrinated horse blood (HB), BHI supplemented with hemin and menadione (BHI-HM) (Thornton et al., 2012), and supplemented TYG (TYGS) (Goodman et al....
[...]
TL;DR: It is hypothesized that most THMs treat diseases via three mechanisms: metabolizing into active metabolites by the action of gut microbiota, regulation of Gut microbiota balance, and regulating the fermentation products of the gut microbes.
Abstract: Traditional Herbal Medicine (THM) has been used for thousands of years, and is popular worldwide due to its effectiveness in a variety of diseases. THM has also formed the basis of the discovery of modern drugs like artemisinin and paclitaxel. However, at present, studies that focus on development in the field of THM are stagnant because currently, the effective ingredients in the herbal formulations and the ambiguity of the underlying mechanisms of action are unknown. In this review, we have investigated the studies available that focused on the efficacy, active ingredients and bioavailability of THM, and the function of gut microbiota in THM-mediated treatment of disease. We hypothesized that most THMs treat diseases via three mechanisms: (1) metabolizing into active metabolites by the action of gut microbiota, (2) regulation of gut microbiota balance, and (3) regulating the fermentation products of the gut microbes. Therefore, focusing on these aspects can help elucidate the pharmacodynamic constituents of THM preparations, and their therapeutic mechanisms of action.
26 citations
References
More filters
TL;DR: A new criterion for triggering the extension of word hits, combined with a new heuristic for generating gapped alignments, yields a gapped BLAST program that runs at approximately three times the speed of the original.
Abstract: The BLAST programs are widely used tools for searching protein and DNA databases for sequence similarities. For protein comparisons, a variety of definitional, algorithmic and statistical refinements described here permits the execution time of the BLAST programs to be decreased substantially while enhancing their sensitivity to weak similarities. A new criterion for triggering the extension of word hits, combined with a new heuristic for generating gapped alignments, yields a gapped BLAST program that runs at approximately three times the speed of the original. In addition, a method is introduced for automatically combining statistically significant alignments produced by BLAST into a position-specific score matrix, and searching the database using this matrix. The resulting Position-Specific Iterated BLAST (PSIBLAST) program runs at approximately the same speed per iteration as gapped BLAST, but in many cases is much more sensitive to weak but biologically relevant sequence similarities. PSI-BLAST is used to uncover several new and interesting members of the BRCT superfamily.
70,111 citations
TL;DR: The sensitivity of the commonly used progressive multiple sequence alignment method has been greatly improved and modifications are incorporated into a new program, CLUSTAL W, which is freely available.
Abstract: The sensitivity of the commonly used progressive multiple sequence alignment method has been greatly improved for the alignment of divergent protein sequences. Firstly, individual weights are assigned to each sequence in a partial alignment in order to down-weight near-duplicate sequences and up-weight the most divergent ones. Secondly, amino acid substitution matrices are varied at different alignment stages according to the divergence of the sequences to be aligned. Thirdly, residue-specific gap penalties and locally reduced gap penalties in hydrophilic regions encourage new gaps in potential loop regions rather than regular secondary structure. Fourthly, positions in early alignments where gaps have been opened receive locally reduced gap penalties to encourage the opening up of new gaps at these positions. These modifications are incorporated into a new program, CLUSTAL W which is freely available.
63,427 citations
"The effect of environmental conditi..." refers methods in this paper
...Sequences were aligned using ClustalW [46] or T-Coffee [47]....
[...]
TL;DR: This study enters into the particular topics of the relative quantification in real-time RT-PCR of a target gene transcript in comparison to a reference gene transcript and presents a new mathematical model that needs no calibration curve.
Abstract: Use of the real-time polymerase chain reaction (PCR) to amplify cDNA products reverse transcribed from mRNA is on the way to becoming a routine tool in molecular biology to study low abundance gene expression. Real-time PCR is easy to perform, provides the necessary accuracy and produces reliable as well as rapid quantification results. But accurate quantification of nucleic acids requires a reproducible methodology and an adequate mathematical model for data analysis. This study enters into the particular topics of the relative quantification in real-time RT–PCR of a target gene transcript in comparison to a reference gene transcript. Therefore, a new mathematical model is presented. The relative expression ratio is calculated only from the real-time PCR efficiencies and the crossing point deviation of an unknown sample versus a control. This model needs no calibration curve. Control levels were included in the model to standardise each reaction run with respect to RNA integrity, sample loading and inter-PCR variations. High accuracy and reproducibility (<2.5% variation) were reached in LightCycler PCR using the established mathematical model.
30,462 citations
TL;DR: A new method for multiple sequence alignment that provides a dramatic improvement in accuracy with a modest sacrifice in speed as compared to the most commonly used alternatives but avoids the most serious pitfalls caused by the greedy nature of this algorithm.
6,727 citations
"The effect of environmental conditi..." refers methods in this paper
...Sequence relationships were analysed using MATGAT [50] and by construction of cladograms using DrawTree [51] with input information derived from dnd output files from T-Coffee....
[...]
...Sequences were aligned using ClustalW [46] or T-Coffee [47]....
[...]
...Notredame C, Higgins DG, Heringa J: T-Coffee: A novel method for fast and accurate multiple sequence alignment....
[...]
TL;DR: Genomic and proteomic analyses have vastly added to understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut.
Abstract: Summary: Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites. Genomic and proteomic analyses have vastly added to our understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense and adapt to nutrient availability, (ii) multiple pump systems to expel toxic substances, and (iii) the ability to influence the host immune system so that it controls other (competing) pathogens. B. fragilis, which accounts for only 0.5% of the human colonic flora, is the most commonly isolated anaerobic pathogen due, in part, to its potent virulence factors. Species of the genus Bacteroides have the most antibiotic resistance mechanisms and the highest resistance rates of all anaerobic pathogens. Clinically, Bacteroides species have exhibited increasing resistance to many antibiotics, including cefoxitin, clindamycin, metronidazole, carbapenems, and fluoroquinolones (e.g., gatifloxacin, levofloxacin, and moxifloxacin).
1,529 citations
"The effect of environmental conditi..." refers background in this paper
...In addition, release of these organisms into other body sites can result in serious complications and they are associated with a range of extraintestinal infections [5]....
[...]