HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (Papers in Press[PDF]) All Versions of this Article: mic.0.028605-0v1 155/7/2296    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Hasegawa, H. Articles by Häse, C. C Search for Related Content PubMed PubMed Citation Articles by Hasegawa, H. Articles by Häse, C. C Agricola Articles by Hasegawa, H. Articles by Häse, C. C

The extracellular metalloprotease of Vibrio tubiashii directly inhibits its extracellular haemolysin

Oregon State University

ABSTRACT

Vibrio tubiashii is a re-emerging pathogen of mollusks that secretes a variety of extracellular products (ECPs), including a metalloprotease and a cytolysin/hemolysin. Previously, we reported that the V. tubiashii hemolysin locus consists of two open reading frames (vthB and vthA), similar to that of the homologous hemolysin genes (vvhB and vvhA) found in V. vulnificus. Here, we demonstrate that the concomitant expression of both V. tubiashii genes resulted in significantly higher hemolytic activities compared to the vthA gene alone. In addition, we created a VthAB- mutant strain of V. tubiashii that was virtually devoid of hemolytic activities in liquid media. Interestingly, significant production of an additional hemolysin(s) was observed on blood plates. Moreover, we previously reported that in V. tubiashii, proteolytic and hemolytic activities are inversely produced during bacterial growth. Here we studied this correlation in more detail and present evidence that the VtpA metalloprotease inhibits hemolytic activities in culture supernatants based on following evidence: (i) loss of metalloprotease activity by either mutation or EDTA inhibition resulted in increased hemolytic activities; (ii) overexpression of the vtpA gene resulted in decreased hemolytic activities; (iii) purified VtpA metalloprotease directly diminished hemolytic activities by purified VthA hemolysin. Importantly, we found not only that vthAB gene expression remained high throughout growth, but also no dramatic differences in vthAB gene expression between the parent and VtpA- mutant strains. Thus, our results strongly suggest that the V. tubiashii metalloprotease directly targets its hemolysin.

¹ E-mail: hasec{at}science.oregonstate.edu