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The small regulatory RNA FasX enhances group A S treptococcus virulence and inhibits pilus expression via serotype‐specific targets
Author(s) -
Danger Jessica L.,
Cao Tram N.,
Cao Tran H.,
Sarkar Poulomee,
Treviño Jeanette,
Pflughoeft Kathryn J.,
Sumby Paul
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12935
Subject(s) - biology , virulence , pilus , serotype , microbiology and biotechnology , rna , gene , gene expression , mutant , genetics
Summary Bacterial pathogens commonly show intra‐species variation in virulence factor expression and often this correlates with pathogenic potential. The group A S treptococcus ( GAS ) produces a small regulatory RNA (s RNA ), FasX , which regulates the expression of pili and the thrombolytic agent streptokinase. As GAS serotypes are polymorphic regarding (a) FasX abundance, (b) the fibronectin, collagen, T ‐antigen ( FCT ) region of the genome, which contains the pilus genes (nine different FCT ‐types), and (c) the streptokinase‐encoding gene ( ska ) sequence (two different alleles), we sought to test whether FasX regulates pilus and streptokinase expression in a serotype‐specific manner. Parental, fasX mutant and complemented derivatives of serotype M 1 ( ska ‐2, FCT ‐2), M 2 ( ska ‐1, FCT ‐6), M6 ( ska ‐2, FCT ‐1) and M 28 ( ska ‐1, FCT ‐4) isolates were compared. While FasX reduced pilus expression in each serotype, the molecular basis differed, as FasX bound, and inhibited the translation of, different FCT ‐region m RNA s. FasX enhanced streptokinase expression in each serotype, although the degree of regulation varied. Finally, we established that the regulation afforded by FasX enhances GAS virulence, assessed by a model of bacteremia using human plasminogen‐expressing mice. Our data are the first to identify and characterize serotype‐specific regulation by an s RNA in GAS , and to show an s RNA directly contributes to GAS virulence.