Open AccessRole of protease maturation lipoprotein in osmoadaptation of S treptococcus mutans
Author(s) -
Kunii Maiko,
Arimoto Takafumi,
Hasegawa Tokuji,
Kuwata Hirotaka,
Igarashi Takeshi
Publication year - 2014
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 - 10.1111/1574-6968.12477
Subject(s) - streptococcus mutans , protease , mutant , biology , osmotic concentration , osmotic shock , growth medium , microbiology and biotechnology , osmotic pressure , bacteria , strain (injury) , brain heart infusion , biochemistry , enzyme , gene , genetics , anatomy , agar
Osmoadaptation may be an important trait for the pathogenicity of S treptococcus mutans . However, how this organism adapts to changes in osmolality in the oral cavity remains unclear. In this study, we showed that S . mutans utilizes K + for osmoadaptation, in which protease maturation lipoprotein ( P rt M ) plays an important role. Although growth of the wild‐type strain was impaired in a hyperosmotic medium [brain heart infusion ( BHI ) containing 0.3 M N a C l] compared with that in an unmodified BHI , the prt M mutant grew much more poorly in 0.3 M N a C l BHI . Comparison of growth behavior in the hyperosmotic medium supplemented with different osmoprotectants revealed that only the addition of K + allowed the bacteria to overcome the impairment of growth caused by the high osmolality. These results suggest that K + is an important compatible solute for S . mutans . Moreover, K + ‐associated recovery of growth was not observed for the prt M mutant, indicating that P rt M plays a critical role in the utilization of K + . Quantitative reverse‐transcriptase polymerase chain reaction analysis showed that prt M was induced by osmotic stress, implying that prt M is an osmoresponsive gene. These findings suggest that K + is an important compatible solute for S . mutans , and that the osmoresponsive lipoprotein P rt M is involved in K + utilization, contributing to osmoadaptation of S . mutans .