Complete genome sequence of enterohemorrhagic Escherichia coli O157:H7 and genomic comparison with a laboratory strain K-12.
Escherichia coli O157:H7 is a major food-borne infectious pathogen that causes diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. Here we report the complete chromosome sequence of an O157:H7 strain isolated from the Sakai outbreak, and the results of genomic comparison with a benign laboratory strain, K-12 MG1655. The chromosome is 5.5 Mb in size, 859 Kb larger than that of K-12. We identified a 4.1-Mb sequence highly conserved between the two strains, which may represent the fundamental backbone of the E. coli chromosome. The remaining 1.4-Mb sequence comprises of O157:H7-specific sequences, most of which are horizontally transferred foreign DNAs. The predominant roles of bacteriophages in the emergence of O157:H7 is evident by the presence of 24 prophages and prophage-like elements that occupy more than half of the O157:H7-specific sequences. The O157:H7 chromosome encodes 1632 proteins and 20 tRNAs that are not present in K-12. Among these, at least 131 proteins are assumed to have virulence-related functions. Genome-wide codon usage analysis suggested that the O157:H7-specific tRNAs are involved in the efficient expression of the strain-specific genes. A complete set of the genes specific to O157:H7 presented here sheds new insight into the pathogenicity and the physiology of O157:H7, and will open a way to fully understand the molecular mechanisms underlying the O157:H7 infection.
Department of Microbiology, Miyazaki Medical College, Kiyotake, Japan. thayash@fc.miyazaki-med.ac.jp
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Hayashi
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Makino
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Ohnishi
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Kurokawa
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Ishii
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Yokoyama
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Han
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Ohtsubo
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Nakayama
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Murata
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Tanaka
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Tobe
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Iida
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Takami
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Honda
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Sasakawa
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Ogasawara
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Yasunaga
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Kuhara
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Shiba
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Hattori
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Shinagawa
D001426:Bacterial Proteins / Q000235:genetics; D001482:Base Composition; D001483:Base Sequence; D004269:DNA, Bacterial; D004270:DNA, Circular; D004196:Disease Outbreaks; D004926:Escherichia coli / Q000235:genetics; D004927:Escherichia coli Infections / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000235:genetics* / Q000472:pathogenicity; D019143:Evolution, Molecular; D005815:Genetic Code; D016680:Genome, Bacterial; D020071:Interspersed Repetitive Sequences; D008242:Lysogeny; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012329:RNA, Bacterial / Q000235:genetics; D014774:Virulence / Q000235:genetics
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004270:DNA, Circular; D012329:RNA, Bacterial