Host-like carbohydrates promote bloodstream survival of Vibrio vulnificus in vivo.
Bottom Line: Here we demonstrate that sialic acid-like molecules are present on the lipopolysaccharide of V. vulnificus, are required for full motility and biofilm formation, and also contribute to the organism's natural resistance to polymyxin B.Further experiments in a murine model of intravenous V. vulnificus infection demonstrated that expression of nonulosonic acids had a striking benefit for bacterial survival during bloodstream infection and dissemination to other tissues in vivo.In fact, levels of bacterial persistence in the blood corresponded to the overall levels of these molecules expressed by V. vulnificus isolates.
Affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.Show MeSH
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Mentions: V. vulnificus CMCP6 and YJ016 contain phylogenetically distinct clusters predicted to be involved in the synthesis of NulO molecules. Three common steps of NAB pathways across the three domains of life are catalyzed by homologs of CMP-N-acetylneuraminic acid synthetase (Nab1), N-acetylneuraminic acid synthase (Nab2), and UDP-N-acetylglucosamine 2-epimerase (Nab3). HPLC analysis previously revealed that strains with a CMCP6-like genotype produced much larger amounts of NulO than those with a YJ016-like genotype (24). In fact, the nab clusters in these strains are highly divergent from one another, with no synteny and limited sequence identity (Fig. 1A). In YJ016, the nab genes are on the positive strand, and in CMCP6, they are on the negative strand. Although the nab genes in V. vulnificus are related to genes encoding a sialic acid (N-acetylneuraminic acid), there is limited sequence identity between NAB pathway components in V. vulnificus and the more well-described enzymes involved in sialic acid synthesis in E. coli K1. For example, CMCP6 Nab1 shares only 38% amino acid identity (E value, 5e−34) with E. coli NeuA, Nab2 shares 44% identity (E value, 3e−91) with E. coli NeuB, and Nab3 shares 40% identity (E value, 9e−84) with E. coli NeuC.
Affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.