Open AccessAn ffh mutant of Streptococcus mutans is viable and able to physiologically adapt to low pH in continuous culture
Author(s) -
Crowley Paula J.,
Svensäter Gunnel,
Snoep Jacky L.,
Bleiweis Arnold S.,
Brady L.Jeannine
Publication year - 2004
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2004.tb09550.x
Subject(s) - mutant , operon , biology , streptococcus mutans , chemostat , microbiology and biotechnology , biochemistry , pep group translocation , wild type , bacteria , gene , genetics
Previously, we described in Streptococcus mutans strain NG8 a 5‐gene operon ( sat ) that includes ffh , the bacterial homologue of the eukaryotic signal recognition particle (SRP) protein, SR54. A mutation in ffh resulted in acid sensitivity but not loss of viability. In the present study, chemostat‐grown cells of the ffh mutant were shown to possess only 26% and 39% of the parental membrane F‐ATPase activity and 55% and 75% of parental glucose–phosphotransferase (PTS) activity when pH‐7 and pH‐5‐grown cells, respectively, were assayed. Two‐dimensional‐gel electrophoretic analyses revealed significant differences in protein profiles between parent and ffh ‐mutant strains at both pH 5 and pH 7. It appears that the loss of active SRP (Ffh) function, while not lethal, results in substantial alterations in cellular physiology that includes acid tolerance.