Read by QxMD icon Read


Scott D Kobayashi, Adeline R Porter, Brett Freedman, Ruchi Pandey, Liang Chen, Barry N Kreiswirth, Frank R DeLeo
Carbapenem-resistant Klebsiella pneumoniae is a problem worldwide. A carbapenem-resistant K. pneumoniae lineage classified as multilocus sequence type 258 (ST258) is prominent in the health care setting in many regions of the world, including the United States. ST258 strains can be resistant to virtually all clinically useful antibiotics; treatment of infections caused by these organisms is difficult, and mortality is high. As a step toward promoting development of new therapeutics for ST258 infections, we tested the ability of rabbit antibodies specific for ST258 capsule polysaccharide to enhance human serum bactericidal activity and promote phagocytosis and killing of these bacteria by human neutrophils...
March 13, 2018: MBio
Alexander P Pintara, Christine J D Guglielmino, Irani U Rathnayake, Flavia Huygens, Amy V Jennison
Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen, where serotype O157:H7 is typically associated with severe disease. Australia is unique in its STEC epidemiology as severe cases are typically associated with non-O157 serogroups, and locally acquired O157 isolates are H-negative/non-motile. The H-negative phenotype and reduced severity of disease when compared to H7/motile strains are distinct features of O157 Australian strains but the molecular mechanism behind this phenotype has not been reported...
January 24, 2018: Journal of Clinical Microbiology
Jochen Schmid
The distinct biosynthesis pathways for microbial exopolysaccharide production provide different engineering strategies to tailor the chemical structures of the final polymers. This review focuses on the latest insights in the various pathways and identifies bottlenecks as well as promising targets for tailoring microbial polysaccharide production. The main engineering strategies includes the combinatorial assembly of glycosyltransferases and engineering of the Wzx and Wzy proteins for flipping of repeating units as well as polymerization...
January 17, 2018: Current Opinion in Biotechnology
Shuang Yang, Daoyi Xi, Fuyi Jing, Deju Kong, Junli Wu, Lu Feng, Boyang Cao, Lei Wang
Capsular polysaccharides (CPSs), or K-antigens, are the major surface antigens of Escherichia coli. More than 80 serologically unique K-antigens are classified into four groups (Groups 1-4) of capsules. Group 1 and 4 contain the Wzy-dependent polymerization pathway and the gene clusters are in the order galF to gnd; Group 2 and 3 contain the ABC transporter-dependent pathway and the gene clusters consist of three regions, region 1, 2 and 3. Little is known about the variations among the gene clusters. In this study, nine serotypes of K-antigen gene clusters (K2ab, K11, K20, K24, K38, K84, K92, K96, and K102), were sequenced and correlated with their CPS chemical structures...
January 22, 2018: Canadian Journal of Microbiology
Xiaochun Huang, Chang Chen, Chunhua Ren, Yingying Li, Yiqin Deng, Yiying Yang, Xiongqi Ding
Colanic acid (CA) is a group I extracellular polysaccharide (EPS) that contributes to resistance against adverse environments in many members of the Enterobacteriaceae. In the present study, a genetic locus EPSC putatively involved in CA biosynthesis was identified in Vibrio alginolyticus ZJ-51, which undergoes colony morphology variation between translucent/smooth (ZJ-T) and opaque/rugose (ZJ-O). EPSC in ZJ-T carries 21 ORFs and resembles the CA cluster of Escherichia coli K-12. The deletion of EPSC led to decreased EPS and biofilm formation in both genetic backgrounds but no alternation of lipopolysaccharide...
January 2018: Biofouling
Małgorzata Marczak, Andrzej Mazur, Piotr Koper, Kamil Żebracki, Anna Skorupska
Rhizobia dwell and multiply in the soil and represent a unique group of bacteria able to enter into a symbiotic interaction with plants from the Fabaceae family and fix atmospheric nitrogen inside de novo created plant organs, called nodules. One of the key determinants of the successful interaction between these bacteria and plants are exopolysaccharides, which represent species-specific homo- and heteropolymers of different carbohydrate units frequently decorated by non-carbohydrate substituents. Exopolysaccharides are typically built from repeat units assembled by the Wzx/Wzy-dependent pathway, where individual subunits are synthesized in conjunction with the lipid anchor undecaprenylphosphate (und-PP), due to the activity of glycosyltransferases...
December 1, 2017: Genes
Johanna J Kenyon, Anastasiya A Kasimova, Anna Notaro, Nikolay P Arbatsky, Immacolata Speciale, Alexander S Shashkov, Cristina De Castro, Ruth M Hall, Yuriy A Knirel
Structures of capsular polysaccharides of Acinetobacter baumannii isolates carrying KL13 and KL73 gene clusters were established. The closely related KL73 and KL13 gene clusters differ only by one gene in the module responsible for synthesis of the non-2-ulosonic acids. The K13 and K73 polysaccharides differ only in a single side-chain sugar, which is either 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-altro- or -d-glycero-l-altro-non-2-ulosonic acid [di-N-acetylated forms of acinetaminic acid (Aci5Ac7Ac) or 8-epiacinetaminic acid (8eAci5Ac7Ac), respectively]...
November 27, 2017: Carbohydrate Research
Hong Wang, Han Zheng, Qun Li, Yanmei Xu, Jianping Wang, Pengcheng Du, Xinqiong Li, Xiang Liu, Ling Zhang, Nianli Zou, Guodong Yan, Zhengdong Zhang, Huaiqi Jing, Jianguo Xu, Yanwen Xiong
Escherichia albertii is a newly described and emerging diarrheagenic pathogen responsible for outbreaks of gastroenteritis. Serotyping plays an important role in diagnosis and epidemiological studies for pathogens of public health importance. The diversity of O-antigen biosynthesis gene clusters (O-AGCs) provides the primary basis for serotyping. However, little is known about the distribution and diversity of O-AGCs of E. albertii strains. Here, we presented a complete sequence set for the O-AGCs from 52 E...
2017: Frontiers in Microbiology
Xinxin Zhao, Qinlong Dai, Renyong Jia, Dekang Zhu, Mafeng Liu, Mingshu Wang, Shun Chen, Kunfeng Sun, Qiao Yang, Ying Wu, Anchun Cheng
Non-typhoidal Salmonella includes thousands of serovars that are leading causes of foodborne diarrheal illness worldwide. In this study, we constructed three bivalent vaccines for preventing both Salmonella Typhimurium and Salmonella Newport infections by using the aspartate semialdehyde dehydrogenase (Asd)-based balanced-lethal vector-host system. The constructed Asd(+) plasmid pCZ11 carrying a subset of the Salmonella Newport O-antigen gene cluster including the wzx-wbaR-wbaL-wbaQ-wzy-wbaW-wbaZ genes was introduced into three Salmonella Typhimurium mutants: SLT19 (Δasd) with a smooth LPS phenotype, SLT20 (Δasd ΔrfbN) with a rough LPS phenotype, and SLT22 (Δasd ΔrfbN ΔpagL::T araC PBADrfbN) with a smooth LPS phenotype when grown with arabinose...
2017: Frontiers in Cellular and Infection Microbiology
Neil Ravenscroft, Aneesa Omar, Jason Hlozek, Cesarina Edmonds-Smith, Rainer Follador, Fabio Serventi, Gerd Lipowsky, Michelle M Kuttel, Paola Cescutti, Amirreza Faridmoayer
Streptococcus pneumoniae is a globally important encapsulated human pathogen with approximately 100 different serotypes recognized. Serogroup 23 consists of serotype 23F, present in licensed vaccines, and emerging serotypes 23A and 23B. Here, we report the previously unknown structures of the pneumococcal capsular polysaccharides serotype 23A and 23B determined using genetic analysis, NMR spectroscopy, composition and linkage analysis and Smith degradation (of polysaccharide 23A). The structure of the serotype 23A capsular polysaccharide is: →4)-β-D-Glcp-(1→3)-[[α-L-Rhap-(1→2)]-[Gro-(2→P→3)]-β-D-Galp-(1→4)]-β-L-Rhap-(1→...
August 18, 2017: Carbohydrate Research
Xiang Yu, Agnieszka Torzewska, Xinjie Zhang, Zhiqiu Yin, Dominika Drzewiecka, Hengchun Cao, Bin Liu, Yuriy A Knirel, Antoni Rozalski, Lei Wang
Proteus species are well-known opportunistic pathogens frequently associated with skin wound and urinary tract infections in humans and animals. O antigen diversity is important for bacteria to adapt to different hosts and environments, and has been used to identify serotypes of Proteus isolates. At present, 80 Proteus O-serotypes have been reported. Although the O antigen structures of most Proteus serotypes have been identified, the genetic features of these O antigens have not been well characterized. The O antigen gene clusters of Proteus species are located between the cpxA and secB genes...
2017: PloS One
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 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...
September 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
M Rangarajan, J Aduse-Opoku, N A Paramonov, A Hashim, M A Curtis
Porphyromonas gingivalis is a Gram-negative black pigmenting anaerobe that is unable to synthesize heme [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. Porphyromonas gingivalis expresses several proteinaceous hemin-binding sites, which are important in the binding/transport of heme/hemin from the host. It also synthesizes several virulence factors, namely cysteine-proteases Arg- and Lys-gingipains and two lipopolysaccharides (LPS), O-LPS and A-LPS...
October 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
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"