Bacterial Exopolysaccharides

Knirel, Yuriy A.; Calsteren, Marie‐Rose Van

doi:10.1016/b978-0-12-819475-1.00005-5

Cited by 9 publications

(9 citation statements)

References 478 publications

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“…The 5093 phage RBP has previously been reported to exhibit an esterase-like domain at the C-terminal end of the protein ( Figure 5 ) [ 25 ]. Several saccharidic moieties in the Gram-positive cell wall (EPS, CWPS, and teichoic acids) may incorporate (phosphodi)ester-linked components; thus it is plausible that the esterase domain is functional with respect to one or more of these cell wall polysaccharides [ 30 , 31 ]. All analyzed Bpps encoded by Moineauvirus and Brussowvirus members harbor RBP domains with structural relatedness to those of the lactococcal phage TP901–1 (PDB 4I0S_A), Listeria phage PSA (6R5W_C), and/or Staphylococcus phage phi80 alpha (C), with at least 97% probability ( Figure 5 ).…”

Section: Interactions Of Dairy Streptococcal Phages and Their Hostsmentioning

confidence: 99%

Biodiversity of Phages Infecting the Dairy Bacterium Streptococcus thermophilus

et al. 2021

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Streptococcus thermophilus-infecting phages represent a major problem in the dairy fermentation industry, particularly in relation to thermophilic production systems. Consequently, numerous studies have been performed relating to the biodiversity of such phages in global dairy operations. In the current review, we provide an overview of the genetic and morphological diversity of these phages and highlight the source and extent of genetic mosaicism among phages infecting this species through comparative proteome analysis of the replication and morphogenesis modules of representative phages. The phylogeny of selected phage-encoded receptor binding proteins (RBPs) was assessed, indicating that in certain cases RBP-encoding genes have been acquired separately to the morphogenesis modules, thus highlighting the adaptability of these phages. This review further highlights the significant advances that have been made in defining emergent genetically diverse groups of these phages, while it additionally summarizes remaining knowledge gaps in this research area.

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Section: Interactions Of Dairy Streptococcal Phages and Their Hostsmentioning

confidence: 99%

Biodiversity of Phages Infecting the Dairy Bacterium Streptococcus thermophilus

et al. 2021

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“…Bacterial protection from external antimicrobial threats is known to be significantly enhanced by the presence of a complex polysaccharide matrix, known as the capsular polysaccharide (CPS). CPS forms the external-most layer of the bacterial cell envelope and is comprised of high molecular weight polymers of repeating oligosaccharide units (K units) 5 , 6 . CPS is a primary virulence determinant and its presence is critical for protection against complement-mediated killing and opsonophagocytosis 7 – 10 , as well as for mediating resistance to desiccation and other antimicrobials 11 – 13 .…”

Section: Introductionmentioning

confidence: 99%

The Wzi outer membrane protein mediates assembly of a tight capsular polysaccharide layer on the Acinetobacter baumannii cell surface

Tickner

Hawas

Totsika

et al. 2021

Sci Rep

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Identification of novel therapeutic targets is required for developing alternate strategies to treat infections caused by the extensively drug-resistant bacterial pathogen, Acinetobacter baumannii. As capsular polysaccharide (CPS) is a prime virulence determinant required for evasion of host immune defenses, understanding the pathways for synthesis and assembly of this discrete cell-surface barrier is important. In this study, we assess cell-bound and cell-free CPS material from A. baumannii AB5075 wildtype and transposon library mutants and demonstrate that the Wzi outer membrane protein is required for the proper assembly of the CPS layer on the cell surface. Loss of Wzi resulted in an estimated 4.4-fold reduction in cell-associated CPS with a reciprocal increase in CPS material shed in the extracellular surrounds. Transmission electron microscopy revealed a disrupted CPS layer with sparse patches of CPS on the external face of the outer membrane when Wzi function was lost. However, this genotype did not have a significant effect on biofilm formation. Genetic analysis demonstrated that the wzi gene is ubiquitous in the species, though the nucleotide sequences were surprisingly diverse. Though divergence was not concomitant with variation at the CPS biosynthesis K locus, an association between wzi type and the first sugar of the CPS representing the base of the structure most likely to interact with Wzi was observed.

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“…This high structural diversity in the species is predominantly due to extensive variation in the genetic content at the chromosomal K locus (KL) that drives CPS biosynthesis [ 13 ], and to date, more than 140 KL gene clusters have been identified at this location [ 14 ]. Chemical structures are now available for more than 40 different A. baumannii CPSs [ 15 ], and generally, the resolved CPS structures are consistent with the genes located at the K locus. One aspect of the diversity is that several structures have been found to include sugar substrates that are either only found in A. baumannii or otherwise rarely occur in nature; for example, 5,7-di-acetylacinetaminic acid [ 16 ], 5,7-di-acetyl-8-epiacinetaminic acid [ 17 ], N -acetylviosamine [ 18 ], and 6-deoxy- l -talose [ 19 ].…”

Section: Introductionmentioning

confidence: 93%

Acinetobacter baumannii K106 and K112: Two Structurally and Genetically Related 6-Deoxy-l-talose-Containing Capsular Polysaccharides

Kasimova

Arbatsky

Tickner

et al. 2021

IJMS

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Whole genome sequences of two Acinetobacter baumannii clinical isolates, 48-1789 and MAR24, revealed that they carry the KL106 and KL112 capsular polysaccharide (CPS) biosynthesis gene clusters, respectively, at the chromosomal K locus. The KL106 and KL112 gene clusters are related to the previously described KL11 and KL83 gene clusters, sharing genes for the synthesis of l-rhamnose (l-Rhap) and 6-deoxy-l-talose (l-6dTalp). CPS material isolated from 48-1789 and MAR24 was studied by sugar analysis and Smith degradation along with one- and two-dimensional 1H and 13C NMR spectroscopy. The structures of K106 and K112 oligosaccharide repeats (K units) l-6dTalp-(1→3)-D-GlcpNAc tetrasaccharide fragment share the responsible genes in the respective gene clusters. The K106 and K83 CPSs also have the same linkage between K units. The KL112 cluster includes an additional glycosyltransferase gene, Gtr183, and the K112 unit includes α l-Rhap side chain that is not found in the K106 structure. K112 further differs in the linkage between K units formed by the Wzy polymerase, and a different wzy gene is found in KL112. However, though both KL106 and KL112 share the atr8 acetyltransferase gene with KL83, only K83 is acetylated.

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Bacterial Exopolysaccharides

Cited by 9 publications

References 478 publications

Biodiversity of Phages Infecting the Dairy Bacterium Streptococcus thermophilus

Biodiversity of Phages Infecting the Dairy Bacterium Streptococcus thermophilus

The Wzi outer membrane protein mediates assembly of a tight capsular polysaccharide layer on the Acinetobacter baumannii cell surface

Acinetobacter baumannii K106 and K112: Two Structurally and Genetically Related 6-Deoxy-l-talose-Containing Capsular Polysaccharides

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