Genetic characterization of the natural SigB variants found in clinical isolates of Staphylococcus aureus.
The SigB concentrations in clinical isolates of Staphylococcus aureus were measured to examine their correlation with the antibiotic resistance. The SigB concentrations in methicillin-resistant S. aureus (MRSA) were higher than in the control strain, N315, and many of methicillin-susceptible S. aureus (MSSA). Sequencing analyses of the sigB genes revealed that the strains exhibiting the high SigB concentrations have three amino acid substitutions in SigB: I11V, D141N, and Q256K. Further analysis using isogenic mutants demonstrated that D141N (or both D141N and Q256K) is essential to maintain the high SigB concentration. These substitutions affected the UV tolerance, but had no effect on the antibiotic resistance. The SigB activity was affected by these substitutions toward the stationary phase, but not during the transient heat shock response.
Inose
Yumiko
Y
Institute of Basic Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Japan.
Takeshita
Sayaka L
SL
Hidaka
Toshie
T
Higashide
Masato
M
Maruyama
Atsushi
A
Hayashi
Hideo
H
Morikawa
Kazuya
K
Ohta
Toshiko
T
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D006801:Humans; D012808:Sigma Factor / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000528:radiation effects; D014466:Ultraviolet Rays
D001426:Bacterial Proteins; C079011:SigB protein, Bacteria; D012808:Sigma Factor