emm1/sequence type 28 strains of group A streptococci that express covR at early stationary phase are associated with increased growth and earlier SpeB secretion.
Streptococcus pyogenes (group A streptococcus [GAS]) is a versatile human pathogen, and emm1/sequence type 28 (ST28) is the most frequently isolated type from GAS infections. The emm1/ST28 strain is associated with necrotizing fasciitis and streptococcal toxic shock syndrome. Growth-phase regulation is one of the important regulatory mechanisms in GAS, which controls gene expression at restricted phases of growth. CovRS, a two-component regulatory system, is considered the regulator of streptococcal pyrogenic exotoxin B (SpeB) and is thought to be activated in the exponential phase of growth. In the present study, Northern hybridization analysis showed that 52% of the analyzed GAS strains expressed covR at the exponential phase, but 48% of the strains expressed covR at the early stationary phase of growth. Strains transcribing covR at the early stationary phase showed better growth and earlier SpeB expression than the other group of strains. Multilocus sequence typing and pulsed-field gel electrophoresis analysis showed only emm1/ST28 strains (which comprise a clonal cluster) were expressing covR at the early stationary phase of growth, indicating that emm1/ST28 strains have special characteristics which may be related to their worldwide distribution.
Chiang-Ni
Chuan
C
Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Zheng
Po-Xing
PX
Ho
Yueh-Ren
YR
Wu
Hsiu-Mei
HM
Chuang
Woei-Jer
WJ
Lin
Yee-Shin
YS
Lin
Ming-T
MT
Liu
Ching-Chuan
CC
Wu
Jiunn-Jong
JJ
D000942:Antigens, Bacterial / Q000235:genetics*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics*; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005098:Exotoxins / Q000096:biosynthesis*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005838:Genotype; D006801:Humans; D012097:Repressor Proteins / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D013290:Streptococcal Infections / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; C432143:CsrR protein, Streptococcus pyogenes; D004269:DNA, Bacterial; D005098:Exotoxins; D012097:Repressor Proteins; C027951:erythrogenic toxin; C014689:streptococcal M protein