This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fontaine, M. C. Articles by Willson, P. J. Search for Related Content PubMed PubMed Citation Articles by Fontaine, M. C. Articles by Willson, P. J.

Investigation of a Novel DNase of Streptococcus suis Serotype 2

Michael C. Fontaine, Jose Perez-Casal, and Philip J. Willson^*

Vaccine & Infectious Disease Organization, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E3, Canada

Received 1 May 2003/ Returned for modification 28 July 2003/ Accepted 23 October 2003

A secreted nuclease, SsnA, was identified in the virulent Streptococcus suis isolate SX332 and subsequently in each of the type strains of capsular serotypes 1 through 9. Screening of 258 porcine clinical isolates from surface (nasal mucosa or palatine tonsil) or internal (joint, brain or other internal organ) locations revealed a significant relationship (P < 0.001) between expression of nuclease and isolation from an internal site. A 3,126-bp gene, ssnA, was identified from a phenotypically nuclease-negative pGh9:ISS1 insertion mutant, and analysis of the predicted SsnA sequence revealed a 35-amino-acid (aa) secretion signal sequence, a 22-aa DNA-binding domain, and a typical gram-positive cell wall sorting motif. A requirement of Ca²⁺ and Mg²⁺ for SsnA activity was determined, and the substrate specificity was found to be for single- and double-stranded linear DNA. Reverse transcription-PCR experiments revealed that ssnA is expressed throughout all stages of S. suis growth, and Western blots with porcine anti-S. suis immune sera against a recombinant, truncated SsnA derivative (rSsnA) confirmed that SsnA is expressed in vivo. Furthermore, anti-rSsnA antibodies were sufficient to neutralize SsnA activity. Analyses of subcellular fractions of SX332 and derived mutants, on DNA-containing polyacrylamide gels and by Western blotting, suggest that SsnA is cell wall located.

Published as number 328 in the Vaccine & Infectious Disease Organization journal series.

Editor: V. J. DiRita

Present address: Moredun Research Institute, Penicuik EH26 0PZ, Scotland, United Kingdom.

This article has been cited by other articles:

• Aranda, J., Garrido, M. E., Cortes, P., Llagostera, M., Barbe, J. (2008). Analysis of the Protective Capacity of Three Streptococcus suis Proteins Induced under Divalent-Cation-Limited Conditions. Infect. Immun. 76: 1590-1598 [Abstract] [Full Text]