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Olaya Rendueles, Marc Garcia-Garcerà, Bertrand Néron, Marie Touchon, Eduardo P C Rocha
Extracellular capsules constitute the outermost layer of many bacteria, are major virulence factors, and affect antimicrobial therapies. They have been used as epidemiological markers and recently became vaccination targets. Despite the efforts to biochemically serotype capsules in a few model pathogens, little is known of their taxonomic and environmental distribution. We developed, validated, and made available a computational tool, CapsuleFinder, to identify capsules in genomes. The analysis of over 2500 prokaryotic genomes, accessible in a database, revealed that ca...
July 2017: PLoS Pathogens
K Aaron Geno, C Allen Bush, Mengnan Wang, Cheng Jin, Moon H Nahm, Jinghua Yang
Streptococcus pneumoniae expresses capsular polysaccharides (CPSs) to protect itself from opsonophagocytic killing. The genes responsible for capsules synthesized by the Wzy-dependent mechanism, which accounts for 96 of the 98 known pneumococcal capsule types, are encoded in a chromosomal region known as the cps locus. The nucleotide sequence in this region has been determined for all serotypes. In contrast, not all CPS structures have been defined. The structure of the serotype 35C polysaccharide was recently reported, but the presence of O-acetyltransferase genes in the serotype 35C cps locus suggested that it could be incomplete, as the reported structure contains no O-acetylation...
June 28, 2017: Journal of Clinical Microbiology
Johanna J Kenyon, Alexander S Shashkov, Sof'ya N Senchenkova, Mikhail M Shneider, Bin Liu, Anastasiya V Popova, Nikolay P Arbatsky, Konstantin A Miroshnikov, Lei Wang, Yuriy A Knirel, Ruth M Hall
Acinetobacter baumannii produces a variety of capsular polysaccharides (CPS) via genes located at the chromosomal K locus and some KL gene clusters include genes for the synthesis of specific sugars. The structures of K11 and K83 CPS produced by isolates LUH5545 and LUH5538, which carry related KL11a and KL83 gene clusters, respectively, were established by sugar analysis and one- and two-dimensional (1)H and (13)C NMR spectroscopy. Both CPS contain l-rhamnose (l-Rha) and 6-deoxy-l-talose (l-6dTal), and both KL gene clusters include genes for dTDP-l-Rhap synthesis and a tle (talose epimerase) gene encoding an epimerase that converts dTDP-l-Rhap to dTDP-l-6dTalp...
October 2017: International Journal of Biological Macromolecules
Thomas R Larson, Janet Yother
For many bacteria, including those important in pathogenesis, expression of a surface-localized capsular polysaccharide (CPS) can be critical for survival in host environments. In Gram-positive bacteria, CPS linkage is to either the cytoplasmic membrane or the cell wall. Despite the frequent occurrence and essentiality of these polymers, the exact nature of the cell wall linkage has not been described in any bacterial species. Using the Streptococcus pneumoniae serotype 2 CPS, which is synthesized by the widespread Wzy mechanism, we found that linkage occurs via the reducing end glucose of CPS and the β-D-N-acetylglucosamine (GlcNAc) residues of peptidoglycan (PG)...
May 30, 2017: Proceedings of the National Academy of Sciences of the United States of America
Richard F Collins, Vasileios Kargas, Brad R Clarke, C Alistair Siebert, Daniel K Clare, Peter J Bond, Chris Whitfield, Robert C Ford
Wzz is an integral inner membrane protein involved in regulating the length of lipopolysaccharide O-antigen glycans and essential for the virulence of many Gram-negative pathogens. In all Wzz homologs, the large periplasmic domain is proposed to be anchored by two transmembrane helices, but no information is available for the transmembrane and cytosolic domains. Here we have studied purified oligomeric Wzz complexes using cryoelectron microscopy and resolved the transmembrane regions within a semi-continuous detergent micelle...
May 2, 2017: Structure
Johanna J Kenyon, Anastasiya A Kasimova, Mikhail M Shneider, Alexander S Shashkov, Nikolay P Arbatsky, Anastasiya V Popova, Konstantin A Miroshnikov, Ruth M Hall, Yuriy A Knirel
The whole-genome sequence of the multiply antibiotic resistant Acinetobacter baumannii isolate RCH51 belonging to sequence type ST103 (Institut Pasteur scheme) revealed that the set of genes at the capsule locus, KL24, includes four genes predicted to direct the synthesis of 3-acetamido-3,6-dideoxy-d-galactose (d-Fuc3NAc), and this sugar was found in the capsular polysaccharide (CPS). One of these genes, fdtE, encodes a novel bifunctional protein with an N-terminal FdtA 3,4-ketoisomerase domain and a C-terminal acetyltransferase domain...
March 2017: Microbiology
Shivangi Sachdeva, Raghuvamsi V Palur, Karpagam U Sudhakar, Thenmalarchelvi Rathinavelan
Bacteria evolving resistance against the action of multiple drugs and its ability to disseminate the multidrug resistance trait(s) across various strains of the same bacteria or different bacterial species impose serious threat to public health. Evolution of such multidrug resistance is due to the fact that, most of the antibiotics target bacterial survival mechanisms which exert selective pressure on the bacteria and aids them to escape from the action of antibiotics. Nonetheless, targeting bacterial virulence strategies such as bacterial surface associated polysaccharides biosynthesis and their surface accumulation mechanisms may be an attractive strategy, as they impose less selective pressure on the bacteria...
2017: Frontiers in Microbiology
Minnie Rangarajan, Joseph Aduse-Opoku, Nikolay A Paramonov, Ahmed Hashim, Michael A Curtis
Porphyromonas gingivalis is a Gram-negative black pigmenting anaerobe unable to synthesise haem (Fe (II)-protoporphyrin IX) or hemin (Fe(III)-protoporphyrin IX-Cl) which are important growth/virulence-factors, and must therefore derive them from the host P. gingivalis expresses several proteinaceous hemin -binding-sites which are important in the binding/ transport of haem/hemin from the host. P. gingivalis also synthesises several virulence factors, namely cysteine-proteases Arg- and Lys-gingipains and two lipopolysaccharides (LPS), O-LPS and A-LPS...
January 20, 2017: Molecular Oral Microbiology
Johanna J Kenyon, Anastasiya A Kasimova, Mikhail Shneider, Alexander S Shashkov, Nikolay P Arbatsky, Anastasiya V Popova, Konstantin A Miroshnikov, Ruth M Hall, Yuriy A Knirel
The whole genome sequence of the multiply antibiotic resistant Acinetobacter baumannii isolate RCH51 belonging to sequence type ST103 (Institut Pasteur scheme) revealed that the set of genes at the capsule locus, KL24, includes four genes predicted to direct the synthesis of 3-acetamido-3,6-dideoxy-D-galactose (D-Fuc3NAc) and this sugar was found in the capsular polysaccharide (CPS). One of these genes, fdtE, encodes a novel bifunctional protein with an N-terminal FdtA 3,4-ketoisomerase domain and a C-terminal acetyltransferase domain...
January 17, 2017: Microbiology
James Gurney, Lafi Aldakak, Alex Betts, Claire Gougat-Barbera, Timothée Poisot, Oliver Kaltz, Michael E Hochberg
Numerous theoretical and experimental studies have investigated antagonistic co-evolution between parasites and their hosts. Although experimental tests of theory from a range of biological systems are largely concordant regarding the influence of several driving processes, we know little as to how mechanisms acting at the smallest scales (individual molecular and phenotypic changes) may result in the emergence of structures at larger scales, such as co-evolutionary dynamics and local adaptation. We capitalized on methods commonly employed in community ecology to quantify how the structure of community interaction matrices, so-called bipartite networks, reflected observed co-evolutionary dynamics, and how phages from these communities may or may not have adapted locally to their bacterial hosts...
April 2017: Molecular Ecology
Uffe B Skov Sørensen, Kaihu Yao, Yonghong Yang, Hervé Tettelin, Mogens Kilian
Expression of a capsular polysaccharide is considered a hallmark of most invasive species of bacteria, including Streptococcus pneumoniae, in which the capsule is among the principal virulence factors and is the basis for successful vaccines. Consequently, it was previously assumed that capsule production distinguishes S. pneumoniae from closely related commensals of the mitis group streptococci. Based on antigenic and genetic analyses of 187 mitis group streptococci, including 90 recognized serotypes of S...
November 15, 2016: MBio
Alexander S Shashkov, Johanna J Kenyon, Nikolay P Arbatsky, Mikhail M Shneider, Anastasiya V Popova, Konstantin A Miroshnikov, Ruth M Hall, Yuriy A Knirel
Capsular polysaccharides were recovered from four Acinetobacter baumannii isolates, and the following related structures of oligosaccharide repeating units were established by sugar analyses along with 1D and 2D (1)H and (13)C NMR spectroscopy: NIPH 60 and LUH5544 (K43) NIPH 601 (K47) The K locus for capsule biosynthesis in the genome sequences available for NIPH 60 and LUH5544, designated KL43, was found to be related to gene clusters KL47 in NIPH 601 and KL88 in LUH5548. The three clusters share most gene content differing in only a small portion that includes an additional glycosyltransferase genes in KL47 and KL88, as well as genes encoding distinct Wzy polymerases that were found to form the same α-d-GlcpNAc-(1 → 6)-α-d-GlcpNAc linkage in K43 and K47...
November 29, 2016: Carbohydrate Research
Lingyan Li, Xuewei Pan, Xiaoli Cui, Qinghui Sun, Xiaojing Yang, Hongjiang Yang
Phage genomic information and the nature of host-phage interactions are important for phage applications. In this study, Pseudomonas aeruginosa phage K5 is characterized as a linear double-stranded genomic DNA molecule of 93,754 bp with identical 1182-bp direct terminal repeats. Comparative genomic analysis reveals that phage K5 is highly homologous to the "PaP1-like" phages. Thirteen mutants resistant to phage K5 are screened in a transposon mutant library. The disrupted genetic loci are identified as gene Y880_RS05480 encoding a putative O-antigen polymerase Wzy and gene wapH encoding a glycosyltransferase...
December 2016: Journal of Basic Microbiology
Nathan A M Chrismas, Gary Barker, Alexandre M Anesio, Patricia Sánchez-Baracaldo
BACKGROUND: Cyanobacteria are major primary producers in extreme cold ecosystems. Many lineages of cyanobacteria thrive in these harsh environments, but it is not fully understood how they survive in these conditions and whether they have evolved specific mechanisms of cold adaptation. Phormidesmis priestleyi is a cyanobacterium found throughout the cold biosphere (Arctic, Antarctic and alpine habitats). Genome sequencing of P. priestleyi BC1401, an isolate from a cryoconite hole on the Greenland Ice Sheet, has allowed for the examination of genes involved in cold shock response and production of extracellular polymeric substances (EPS)...
2016: BMC Genomics
Susana Merino, Victor Gonzalez, Juan M Tomás
In the Wzx/Wzy-dependent assembled pathway, the assembled O-antigen repeat units are translocated from the cytosolic to the periplasmic face of the inner membrane by a Wzx translocase and then polymerized by the integral membrane protein Wzy to form a glycan chain. We demonstrate that the activity of the Escherichia coli O-antigen polymerase (Wzy) is dependent on the first sugar of the O-antigen repeat unit to produce the O-antigen polymerization and therefore, there is a need for a concerted action with the enzyme transferring the initial HexNAc to undecaprenyl phosphate (UDP-HexNAc: polyprenol-P HexNAc-1-P transferase)...
July 2016: Future Microbiology
Lei Li, Robert L Woodward, Weiqing Han, Jingyao Qu, Jing Song, Cheng Ma, Peng G Wang
Polysaccharides are essential and immunologically relevant components of bacterial cell walls. These biomolecules can be found covalently attached to lipids (e.g., O-polysaccharide (PS) contains undecaprenyl and lipopolysaccharide (LPS) contains lipid A) or noncovalently associated with cell wells (e.g., capsular PS (CPS)). Although extensive genetic studies have indicated that the Wzy-dependent biosynthetic pathway is primarily responsible for producing such polysaccharides, in vitro biochemical studies are needed to determine, for example, which gene product is responsible for catalyzing each step in the pathway, and to reveal molecular details about the Wzx translocase, Wzy polymerase and O-PS chain-length determinant...
July 2016: Nature Protocols
Keding Cheng, Huixia Chui, Larissa Domish, Angela Sloan, Drexler Hernandez, Stuart McCorrister, Alyssia Robinson, Matthew Walker, Lorea A M Peterson, Miles Majcher, Sam Ratnam, David J M Haldane, Sadjia Bekal, John Wylie, Linda Chui, Shaun Tyler, Bianli Xu, Aleisha Reimer, Celine Nadon, J David Knox, Gehua Wang
Mass spectrometry-based phenotypic H-antigen typing (MS-H) combined with whole-genome-sequencing-based genetic identification of H antigens, O antigens, and toxins (WGS-HOT) was used to type 60 clinical Escherichia coli isolates, 43 of which were previously identified as nonmotile, H type undetermined, or O rough by serotyping or having shown discordant MS-H and serotyping results. Whole-genome sequencing confirmed that MS-H was able to provide more accurate data regarding H antigen expression than serotyping...
August 2016: Journal of Clinical Microbiology
Yaoqin Hong, Peter R Reeves
The Wzx/Wzy O-antigen pathway involves synthesis of a repeat unit (O unit) consisting of 3 to 8 sugars on an inner-membrane-embedded lipid carrier. These O units are translocated across the membrane to its periplasmic face by Wzx, while retaining linkage to the carrier, and then polymerized by Wzy to O-antigen polymer, which WaaL ligase transfers to a lipopolysaccharide precursor to complete lipopolysaccharide synthesis, concomitantly releasing the lipid carrier. This lipid carrier is also used for peptidoglycan assembly, and sequestration is known to be toxic...
January 2016: MSphere
Xiaomei Zhao, Guiming Zhao, Ping Wang, Ying Chen, Yanchao Jiao, Adong Luo
OBJECTIVE: To establish a rapid assay to detect enterohemorrhagic Escherichia coli O157 (E. coli O157) and enterohemorrhagic Escherichia coli O104 (E. coli O104) in the legume plants and its products by using the duplex real-time PCR. METHODS: Based on part fragments of E. coli O157 specific gene rfbE and E. coli O104 specific gene wzy, primers and Taq-Man probes were designed. Results DNA (Q157): DNA (O104) = 1 : 3, DNA 2 μL, Master Mix 12.5 μL, primers (10 μmol/L) 1 μL,Taq-Man probes( 10 μmol/L) 0...
March 2016: Wei Sheng Yan Jiu, Journal of Hygiene Research
Atsushi Iguchi, Sunao Iyoda, Kazuko Seto, Hironobu Nishii, Makoto Ohnishi, Hirohisa Mekata, Yoshitoshi Ogura, Tetsuya Hayashi
Serotyping is one of the typing techniques used to classify strains within the same species. O-serogroup diversification shows a strong association with the genetic diversity of O-antigen biosynthesis genes. In a previous study, based on the O-antigen biosynthesis gene cluster (O-AGC) sequences of 184 known Escherichia coli O serogroups (from O1 to O187), we developed a comprehensive and practical molecular O serogrouping (O genotyping) platform using a polymerase chain reaction (PCR) method, named E. coli O-genotyping PCR...
2016: Frontiers in Microbiology
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