Studies on the Vibrio cholerae mucinase complex. I. Enzymic activities associated with the complex325

Stewart‐Tull, D. E. S.; Ollar, Robert A.; Scobie, Tamara S.

doi:10.1099/00222615-22-4-325

Cited by 31 publications

(14 citation statements)

References 26 publications

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“…wt aggregate (c. 325 kDa), which possessed sialidase activity, was isolated as determined by native PAGE and gel filtration chromatography. It was not possible to purify cholerae has demonstrated that this enzyme forms a multi-enzyme complex, which contains other glycosidic and proteolytic activities [36]. Sialidase complexed with other enzymes, including â-galactosidase, is also found in human lysosomes [37].…”

Section: Discussionmentioning

confidence: 99%

Isolation and characterisation of sialidase from a strain of Streptococcus oralis

Byers¹,

Tarelli²,

Homer³

et al. 2000

Journal of Medical Microbiology

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Streptococcus oralis, the most virulent of the viridans streptococci, produces a sialidase and this exo-glycosidase has been implicated in the disease process of a number of pathogens. The sialidase of S. oralis strain AR3 was purified in order to understand the characteristics of this putative virulence determinant. The enzyme isolated as a high mol. wt aggregate (c. 325 kDa) was purified 4520-fold from late exponential phase cultures by a combination of ultrafiltration, ammonium sulphate precipitation, ionexchange and gel filtration chromatography. The sialidase component had a mol. wt of 144 kDa as determined by SDS-PAGE analysis. The purified sialidase released Nacetylneuraminic acid from a range of sialoglycoconjugates including human AE 1 -acid glycoprotein, bovine submaxillary mucin, colominic acid and sialyl-AE2,3-and sialyl-AE2,6-lactose. Also, N-glycolylneuraminic acid was cleaved from bovine submaxillary mucin. The sialidase had a K m of 11.8 ìM for AE 1 -acid glycoprotein, was active over a broad pH range with a pH optimum of 6.0 and cleaved AE2,3-, AE2,6-and AE2-8-sialyl glycosidic linkages with a marked preference for AE2,3-linkages. The enzyme was competitively inhibited by the sialic acid derivative, 2,3-dehydro-N-acetylneuraminic acid, with a K IC of 1.2 ìM. The characteristics of the purified sialidase would support a nutritional role for this enzyme that may be significant in the proliferation of this organism in the oral cavity and at extra-oral sites in association with life-threatening infections.

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Section: Discussionmentioning

confidence: 99%

Isolation and characterisation of sialidase from a strain of Streptococcus oralis

Byers¹,

Tarelli²,

Homer³

et al. 2000

Journal of Medical Microbiology

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“…Clinical streptococcal isolates often secrete NADases (24), and an NADase activity distinct from cholera toxin has been described as an extracellular product of V. cholerae (52). Also, an ORF resembling HvnA and HvnB occurs in the P. aeruginosa genome, suggesting that this organism may also secrete an NADase.…”

Section: Fig 6 Product Analysis Of Nadmentioning

confidence: 99%

“…Thus, the assay used to identify HvnA and HvnB did not distinguish between ARTase or NADase activity. Secreted bacterial ARTases clearly mediate defined effects on certain animal host cells (15,(39)(40)(41), but the role, if any, of secreted NADases in bacterium-host interactions is unknown beyond the observations that clinical streptococcal isolates and Vibrio cholerae secrete NADases (24,52).…”

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Vibrio fischeriGeneshvnAandhvnBEncode Secreted NAD⁺-Glycohydrolases

2001

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HvnA and HvnB are proteins secreted by Vibrio fischeri ES114, an extracellular light organ symbiont of the squid Euprymna scolopes, that catalyze the transfer of ADP-ribose from NAD ؉ to polyarginine. Based on this activity, HvnA and HvnB were presumptively designated mono-ADP-ribosyltransferases (ARTases), and it was hypothesized that they mediate bacterium-host signaling. We have cloned hvnA and hvnB from strain ES114. hvnA appears to be expressed as part of a four-gene operon, whereas hvnB is monocistronic. The predicted HvnA and HvnB amino acid sequences are 46% identical to one another and share 44% and 34% identity,

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“…VPI-2 also encodes sialic acid transport (ORFs VC1777 to VC1779) and catabolism homologues (ORF VC1776 and VC1781 to VC1783), as well as neuraminidase (ORF VC1784), which converts higher-order sialogangliosides to GM1 gangliosides, the receptor for cholera toxin, with the release of sialic acid (6). V. cholerae neuraminidase may also form part of the mucinase complex that hydrolyzes intestinal mucus, enabling the bacterium to move readily to the epithelium (32). Interestingly, none of the four additional published Vibrio species genomes encodes neuraminidase, but they do contain the genes for de novo synthesis of sialic acid, which are absent from V. cholerae (31).…”

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Three Pathogenicity Islands of Vibrio cholerae Can Excise from the Chromosome and Form Circular Intermediates

2008

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Vibrio pathogenicity island-2 (VPI-2) is a 57-kb region integrated at a transfer RNA (tRNA)-serine locus that encompasses VC1758 to VC1809 on the V. cholerae N16961 genome and is present in pandemic isolates. VPI-2 encodes a P4-like integrase, a restriction modification system, a Mu phage-like region, and a sialic acid metabolism region, as well as neuraminidase (VC1784), which is a glycosylhydrolase known to release sialic acid from sialoglycoconjugates to unmask GM1 gangliosides, the receptor for cholera toxin. We examined the tRNA-serine locus among the sequenced V. cholerae genomes and identified five variant VPI-2 regions, four of which retained the sialometabolism region. Three variant VPI-2 regions contained a type three secretion system. By using an inverse nested PCR approach, we found that the VPI-2 region can form an extrachromosomal circular intermediate (CI) molecule after precise excision from its tRNA-serine attachment site. We constructed a knockout mutant of VC1758 (int) with V. cholerae strain N16961 and found that no excision PCR product was produced, indicating that a functional cognate, VPI-2 integrase, is required for excision. The Vibrio seventh pandemic island-I (VSP-I) and VSP-II regions are present in V. cholerae O1 El Tor and O139 serogroup isolates. Novel regions are present at the VSP-I insertion site in strain MZO-3 and at the VSP-II insertion site in strain 623-39. VSP-II is a 27-kb region that integrates at a tRNA-methionine locus, is flanked by direct repeats, and encodes a P4-like integrase. We show that VSP-II can excise and form a CI and that the cognate VSP-II integrase is required for excision. Interestingly, VSP-I is not inserted at a tRNA locus and does encode a XerDC-like recombinase, but similar to VPI-2 and VSP-II, VSP-I does excise from the genome to form a CI. These results show that all three pathogenicity islands can excise from the chromosome, which is likely a first step in their horizontal transfer.

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Studies on the Vibrio cholerae mucinase complex. I. Enzymic activities associated with the complex325

Cited by 31 publications

References 26 publications

Isolation and characterisation of sialidase from a strain of Streptococcus oralis

Isolation and characterisation of sialidase from a strain of Streptococcus oralis

Vibrio fischeriGeneshvnAandhvnBEncode Secreted NAD⁺-Glycohydrolases

Three Pathogenicity Islands of Vibrio cholerae Can Excise from the Chromosome and Form Circular Intermediates

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Studies on the Vibrio cholerae mucinase complex. I. Enzymic activities associated with the complex325

Cited by 31 publications

References 26 publications

Isolation and characterisation of sialidase from a strain of Streptococcus oralis

Isolation and characterisation of sialidase from a strain of Streptococcus oralis

Vibrio fischeriGeneshvnAandhvnBEncode Secreted NAD+-Glycohydrolases

Three Pathogenicity Islands of Vibrio cholerae Can Excise from the Chromosome and Form Circular Intermediates

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Vibrio fischeriGeneshvnAandhvnBEncode Secreted NAD⁺-Glycohydrolases