Acinetobacter baumannii K13 and K73 capsular polysaccharides differ only in K-unit side branches of novel non-2-ulosonic acids: di- N -acetylated forms of either acinetaminic acid or 8-epiacinetaminic acid

Accumulation of Antibiotic Resistance Genes in Carbapenem-Resistant Acinetobacter baumannii Isolates Belonging to Lineage 2, Global Clone 1, from Outbreaks in 2012–2013 at a Tehran Burns Hospital

“…3). However, this small replacement leads to a structural change in the K12 and K13 CPS that are produced (34). Similarly, the KL18 gene cluster is closely related to KL17, which has so far been reported in only a single GC1 lineage 1 isolate, isolate G7 (10).…”

“…3) have been described previously (34,35), though neither has been reported in a GC1 isolate to date. Interestingly, the KL13 gene cluster is closely related to KL12, and both include genes for the synthesis of the rare non-2-ulosonic acid sugar 5,7-di-N-acetylacinetaminic acid, also known as Aci5Ac7Ac (34). The two genetic arrangements differ only in a small segment that includes a single gene (Fig.…”

Comparative Genomics of Acinetobacter baumannii Clinical Strains From Brazil Reveals Polyclonal Dissemination and Selective Exchange of Mobile Genetic Elements Associated With Resistance Genes

“…The K locus also determines the production of complex oligosaccharides units that are exported to the outer membrane of Gram-negative bacteria and includes genes responsible for the synthesis of the exopolysaccharide capsule, the K antigen (Iwashkiw et al, 2012;Kenyon and Hall, 2013;Senchenkova et al, 2015;Holt et al, 2016;Shashkov et al, 2016Shashkov et al, , 2017Kenyon et al, 2017Kenyon et al, , 2019. Despite having the flanking fkpA and lldP genes, none of the strains sequenced here exhibited a unique and fully assembled K locus contig (not shown).…”

Production of the K16 capsular polysaccharide by Acinetobacter baumannii ST25 isolate D4 involves a novel glycosyltransferase encoded in the KL16 gene cluster

“…Correlation of the content of the KL gene clusters to the resolved K unit structures for these strains revealed no other candidates for formation of the -linkage of Pse to the growing K units, and the KpsS proteins were assigned this role. A third glycosyltransferase, Gtr59, that belongs to the KpsS protein family, though a match for this protein could not be found in the Carbohydrate Active enZYmes (CAZY) database, was predicted to link other non-2-ulosonic acids, 5,7-di-N-acetylacinetaminic acid (Aci5Ac7Ac) or 5,7-di-N-acetyl-8-epiacinetaminic acid (8eAci5A7Ac), to the growing K unit [3,19]. Hence, KpsS1/KpsS2 and Gtr59 represent novel Gtr families.…”

“…In A. baumannii, the CPS is composed of blocks of 2-6 monosaccharde residues (K units) that are joined together by a Wzy polymerase to form long chains that decorate the outer surface of the cell. The majority of genes required to direct the synthesis of the CPS are located at the K locus (KL) [2], and different genetic combinations found at this location in different isolates produce structurally distinct CPS [3][4][5][6][7][8][9][10]. The central variable part of the K locus includes genes for glycosyltransferases (Gtrs) that form the linkages between sugar residues in the K unit, as well as those for the translocation (Wzx) and polymerisation (Wzy) of K units to form the CPS chain [2].…”