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Host-like carbohydrates promote bloodstream survival of Vibrio vulnificus in vivo.

Lubin JB, Lewis WG, Gilbert NM, Weimer CM, Almagro-Moreno S, Boyd EF, Lewis AL - Infect. Immun. (2015)

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.

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Affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.

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V. vulnificusnab genetic organization and role of nab2 in NulO biosynthesis. (A) Schematic of the V. vulnificus NulO biosynthetic clusters in YJ016 and CMCP6. Open reading frames and the direction of transcription are designated by arrows. nab1 (encoding a CMP-neuraminic acid synthase homolog), nab2 (encoding an N-acetylneuraminic acid synthase homolog), and nab3 (encoding a UDP-N-acetylglucosamine 2-epimerase homolog) are highlighted. Percentages in shaded areas indicate amino acid identities of translated genes. (B) DMB-HPLC analysis of the CMCP6 WT and isogenic Δnab2 and complemented (Δnab2+pnab2) strains confirmed that nab2 encodes the V. vulnificus NulO synthase. (C and D) NulO expression was normalized to that of 3-deoxy-d-manno-octulosonic acid (Kdo) for quantitative comparisons of NulO expression between strains. Error bars represent standard deviations for three experiments. One-way analysis of variance (ANOVA) with the Bonferroni multiple-comparison posttest (P < 0.05) was used to examine the statistical significance of differences in NulO production. *, P < 0.05; ****, P < 0.0001.
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Figure 1: V. vulnificusnab genetic organization and role of nab2 in NulO biosynthesis. (A) Schematic of the V. vulnificus NulO biosynthetic clusters in YJ016 and CMCP6. Open reading frames and the direction of transcription are designated by arrows. nab1 (encoding a CMP-neuraminic acid synthase homolog), nab2 (encoding an N-acetylneuraminic acid synthase homolog), and nab3 (encoding a UDP-N-acetylglucosamine 2-epimerase homolog) are highlighted. Percentages in shaded areas indicate amino acid identities of translated genes. (B) DMB-HPLC analysis of the CMCP6 WT and isogenic Δnab2 and complemented (Δnab2+pnab2) strains confirmed that nab2 encodes the V. vulnificus NulO synthase. (C and D) NulO expression was normalized to that of 3-deoxy-d-manno-octulosonic acid (Kdo) for quantitative comparisons of NulO expression between strains. Error bars represent standard deviations for three experiments. One-way analysis of variance (ANOVA) with the Bonferroni multiple-comparison posttest (P < 0.05) was used to examine the statistical significance of differences in NulO production. *, P < 0.05; ****, P < 0.0001.

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.


Host-like carbohydrates promote bloodstream survival of Vibrio vulnificus in vivo.

Lubin JB, Lewis WG, Gilbert NM, Weimer CM, Almagro-Moreno S, Boyd EF, Lewis AL - Infect. Immun. (2015)

V. vulnificusnab genetic organization and role of nab2 in NulO biosynthesis. (A) Schematic of the V. vulnificus NulO biosynthetic clusters in YJ016 and CMCP6. Open reading frames and the direction of transcription are designated by arrows. nab1 (encoding a CMP-neuraminic acid synthase homolog), nab2 (encoding an N-acetylneuraminic acid synthase homolog), and nab3 (encoding a UDP-N-acetylglucosamine 2-epimerase homolog) are highlighted. Percentages in shaded areas indicate amino acid identities of translated genes. (B) DMB-HPLC analysis of the CMCP6 WT and isogenic Δnab2 and complemented (Δnab2+pnab2) strains confirmed that nab2 encodes the V. vulnificus NulO synthase. (C and D) NulO expression was normalized to that of 3-deoxy-d-manno-octulosonic acid (Kdo) for quantitative comparisons of NulO expression between strains. Error bars represent standard deviations for three experiments. One-way analysis of variance (ANOVA) with the Bonferroni multiple-comparison posttest (P < 0.05) was used to examine the statistical significance of differences in NulO production. *, P < 0.05; ****, P < 0.0001.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 1: V. vulnificusnab genetic organization and role of nab2 in NulO biosynthesis. (A) Schematic of the V. vulnificus NulO biosynthetic clusters in YJ016 and CMCP6. Open reading frames and the direction of transcription are designated by arrows. nab1 (encoding a CMP-neuraminic acid synthase homolog), nab2 (encoding an N-acetylneuraminic acid synthase homolog), and nab3 (encoding a UDP-N-acetylglucosamine 2-epimerase homolog) are highlighted. Percentages in shaded areas indicate amino acid identities of translated genes. (B) DMB-HPLC analysis of the CMCP6 WT and isogenic Δnab2 and complemented (Δnab2+pnab2) strains confirmed that nab2 encodes the V. vulnificus NulO synthase. (C and D) NulO expression was normalized to that of 3-deoxy-d-manno-octulosonic acid (Kdo) for quantitative comparisons of NulO expression between strains. Error bars represent standard deviations for three experiments. One-way analysis of variance (ANOVA) with the Bonferroni multiple-comparison posttest (P < 0.05) was used to examine the statistical significance of differences in NulO production. *, P < 0.05; ****, P < 0.0001.
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.

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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.

Show MeSH
Related in: MedlinePlus