Open AccessLigand-Signaled Upregulation of Enterococcus faecalis ace Transcription, a Mechanism for Modulating Host- E. faecalis Interaction
Author(s) -
Sreedhar R. Nallapareddy,
Barbara E. Murray
Publication year - 2006
Publication title -
infection and immunity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.508
H-Index - 220
eISSN - 1070-6313
pISSN - 0019-9567
DOI - 10.1128/iai.00476-06
Subject(s) - enterococcus faecalis , bacterial adhesin , biology , laminin , fibronectin , microbiology and biotechnology , messenger rna , transcription (linguistics) , extracellular matrix , escherichia coli , biochemistry , gene , linguistics , philosophy
Enterococcus faecalis , the third most frequent cause of bacterial endocarditis, appears to be equipped with diverse surface-associated proteins showing structural-fold similarity to the immunoglobulin-fold family of staphylococcal adhesins. Among the putativeE. faecalis surface proteins, the previously characterized adhesin Ace, which shows specific binding to collagen and laminin, was detectable in surface protein preparations only after growth at 46°C, mirroring the finding that adherence was observed in 46°C, but not 37°C, grownE. faecalis cultures. To elucidate the influence of different growth and host parameters onace expression, we investigatedace expression usingE. faecalis OG1RF grown in routine laboratory media (brain heart infusion) and found thatace mRNA levels were low in all growth phases. However, quantitative reverse transcription-PCR showed 18-fold-higherace mRNA amounts in cells grown in the presence of collagen type IV compared to the controls. Similarly, a marked increase was observed when cells were either grown in the presence of collagen type I or serum but not in the presence of fibrinogen or bovine serum albumin. The production of Ace after growth in the presence of collagen type IV was demonstrated by immunofluorescence microscopy, mirroring the increasedace mRNA levels. Furthermore, increased Ace expression correlated with increased collagen and laminin adhesion. Collagen-induced Ace expression was also seen in three of three otherE. faecalis strains of diverse origins tested, and thus it appears to be a common phenomenon. The observation of host matrix signal-induced adherence ofE. faecalis may have important implications on our understanding of this opportunistic pathogen.