An evolutionary analysis of nitric oxide reductase gene norV in enterohemorrhagic Escherichia coli O157.
A novel virulence gene, norV, that encodes nitric oxide (NO) reductase, was examined to investigate the emergence of enterohemorrhagic Escherichia coli (EHEC) O157 subgroup C clusters 2 and 3 from subgroup C cluster 1. Deletion of norV occurred at a point between cluster 1 and cluster 2 just after or at the same time that an stx2 bacteriophage, which retains Shiga toxin 2 gene, was inserted into wrbA, which encodes a novel multimeric flavodoxin-like protein, in EHEC O157. Sensitivity of NO to anaerobic growth was correlated with the deletion of norV in all EHEC O157 individuals tested. The C467A mutation of fimH, which encodes minor component of type 1 fimbriae, occurred within cluster 1, not as a transition from cluster 1 to cluster 2, indicating that there is a cluster 1 minority branch that leads to cluster 2. These data refine the evolutionary history of an emerging EHEC O157.
Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chiba 260-8670, Japan. Electronic address: tshimizu@faculty.chiba-u.jp.
Takeshi
T
Shimizu
Division of Bacteriology, Chiba Prefectural Institute of Public Health, 666-2 Nitona, Chiba 260-8715, Japan.
Shinichiro
S
Hirai
Division of Bacteriology, Chiba Prefectural Institute of Public Health, 666-2 Nitona, Chiba 260-8715, Japan.
Eiji
E
Yokoyama
Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chiba 260-8670, Japan.
Kimitoshi
K
Ichimura
Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chiba 260-8670, Japan.
Masatoshi
M
Noda
D019453:Escherichia coli O157 / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D019143:Evolution, Molecular; D017353:Gene Deletion; D005838:Genotype; D009154:Mutation; D009569:Nitric Oxide; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D014774:Virulence / Q000235:genetics
D009569:Nitric Oxide; D010088:Oxidoreductases; C034747:nitric-oxide reductase
Clade; Cluster; EHEC O157; Evolution; Nitric oxide; norV