The influence of HtrA expression on the growth of Streptococcus mutans during acid stress.
When proteins are damaged under stresses conditions, these proteins are either refolded or degraded by quality control system of molecular chaperones and protease. High-temperature requirement A (htrA) is of particular interest because it can perform the roles of both protease and a chaperone. HtrA plays an important role in maintaining the physiological homeostasis of bacteria against environmental stress such as elevated temperature, oxidative and osmotic stress. Inactivation of htrA genes can thus restrict the survival ability of bacteria. These observations suggested that htrA might be responsible for acid tolerance of Streptococcus mutans. In this study, we have generated an htrA mutant and an htrA-complemented strain of S. mutans K7 isolated from a Korean in order to investigate the role of htrA in growth under acidic conditions. In terms of growth under cidic conditions, the htrA mutant exhibited 20% to 23% lower growth than the control group. In addition, glucosyltransferase B and glucosyltransferase C expression levels significantly decreased. When the htrA expression level was restored by adding the htrA gene to the htrA mutant strain, the normal growth phenotype was restored under acid stress. Further, similar results were obtained for S. mutans UA159. Thus, htrA in S. mutans K7, as well as S. mutans UA159, can be concluded to play an important role during acid stress.
Kang
Kyung-hee
KH
Department of Dental Hygiene, Konyang University, Daejeon, 302-718, Korea.
Lee
Jung-Sook
JS
Yoo
Min
M
Jin
Ingnyol
I
D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D002648:Child; D003199:Computer Systems; D003731:Dental Caries / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D004790:Enzyme Induction; D015964:Gene Expression Regulation, Bacterial; D005964:Glucosyltransferases / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007723:Korea; D019344:Lactic Acid / Q000494:pharmacology; D018832:Molecular Chaperones / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000235:genetics / Q000502:physiology*; D017510:Protein Folding; D011993:Recombinant Fusion Proteins / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013295:Streptococcus mutans / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification
D001426:Bacterial Proteins; D018832:Molecular Chaperones; D011993:Recombinant Fusion Proteins; D019344:Lactic Acid; C036655:1,3-alpha-D-glucan synthase; D005964:Glucosyltransferases; C110463:glucosyltransferase C; D010447:Peptide Hydrolases