Bacterial polysaccharides in sickness and in health

Evidence that KpsT, the ATP-binding component of an ATP-binding cassette transporter, is exposed to the periplasm and associates with polymer during translocation of the polysialic acid capsule of Escherichia coli K1

“…Capsule expression is mediated by the 14 gene products of the 17-kb kps cluster (4,19,23). This cluster is divided into three functional regions with the central region 2 responsible for synthesis, activation, and polymerization of the capsular polymer and the flanking regions 1 and 3 involved with translocation of the polymer from its cytoplasmic site of synthesis to the cell surface (4,19,23). We believe translocation to be mediated by a multicomponent complex of proteins, effecting translocation in a single step at sites of membrane fusion (for a review, see reference 4).…”

“…To determine if any other kps components were important for the coprecipitation of KpsT with polySia, pSR340 was transformed into a variety of chromosomal kps mutant strains including chromosomal deletions in kpsM, kpsD, and kpsE, as well as an insertion mutation in kpsC (4,19,23). Extracts from each of these strains were immunoprecipitated and analyzed as described above.…”

A killed, genetically engineered derivative of a wild-type extraintestinal pathogenic E. coli strain is a vaccine candidate

“…Further, certain K antigens (e.g. K1, K5) are poorly immunogenic, which has been speculated to be due to their structural similarities to host antigens [51]. The O-antigen moiety of LPS is also problematic since >150 variants have been described in E. coli strains [52].…”

Identification that KfiA, a Protein Essential for the Biosynthesis of the Escherichia coli K5 Capsular Polysaccharide, is an alpha -UDP-GlcNAc Glycosyltransferase: The Formation of a Membrane Associated K5 Biosynthetic Complex Requires KfiA, KfiB and KfiC

“…The expression of a group 2 capsule is associated with invasive isolates of E. coli and the genetics and biochemistry of these capsules have been studied intensely (1,5). The group 2 K antigen gene cluster consists of 3 regions, 1-3 ( Fig.1) (5). Regions 1 and 3 are conserved between different group 2 antigens and encode 8 proteins responsible for the transport of the polysaccharide from its site of synthesis in the cytoplasm to the external cell surface (6)(7)(8).…”

“…Escherichia coli expresses over 80 capsular polysaccharides, or K antigens, which have been subdivided into 4 groups (1-4) based on a number of biochemical and genetic criteria (4). The expression of a group 2 capsule is associated with invasive isolates of E. coli and the genetics and biochemistry of these capsules have been studied intensely (1,5). The group 2 K antigen gene cluster consists of 3 regions, 1-3 ( Fig.1) (5).…”