Ooka Tadasuke, Ogura Yoshitoshi, Katsura Keisuke, Seto Kazuko, Kobayashi Hideki, Kawano Kimiko, Tokuoka Eisuke, Furukawa Masato, Harada Seiya, Yoshino Shuji, Seto Junji, Ikeda Tetsuya, Yamaguchi Keiji, Murase Kazunori, Gotoh Yasuhiro, Imuta Naoko, Nishi Junichiro, Gomes Tânia A, Beutin Lothar, Hayashi Tetsuya
Department of Microbiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Japan.
Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
Genome Biol Evol. 2015 Nov 3;7(12):3170-9. doi: 10.1093/gbe/evv211.
Escherichia albertii is a recently recognized close relative of Escherichia coli. This emerging enteropathogen possesses a type III secretion system (T3SS) encoded by the locus of enterocyte effacement, similar to enteropathogenic and enterohemorrhagic E. coli (EPEC and EHEC). Shiga toxin-producing strains have also been identified. The genomic features of E. albertii, particularly differences from other Escherichia species, have not yet been well clarified. Here, we sequenced the genome of 29 E. albertii strains (3 complete and 26 draft sequences) isolated from multiple sources and performed intraspecies and intragenus genomic comparisons. The sizes of the E. albertii genomes range from 4.5 to 5.1 Mb, smaller than those of E. coli strains. Intraspecies genomic comparisons identified five phylogroups of E. albertii. Intragenus genomic comparison revealed that the possible core genome of E. albertii comprises 3,250 genes, whereas that of the genus Escherichia comprises 1,345 genes. Our analysis further revealed several unique or notable genetic features of E. albertii, including those responsible for known biochemical features and virulence factors and a possibly active second T3SS known as ETT2 (E. coli T3SS 2) that is inactivated in E. coli. Although this organism has been observed to be nonmotile in vitro, genes for flagellar biosynthesis are fully conserved; chemotaxis-related genes have been selectively deleted. Based on these results, we have developed a nested polymerase chain reaction system to directly detect E. albertii. Our data define the genomic features of E. albertii and provide a valuable basis for future studies of this important emerging enteropathogen.
艾氏埃希菌是最近被认识的大肠杆菌的近缘种。这种新出现的肠道病原体拥有一个由肠细胞损伤位点编码的III型分泌系统（T3SS），类似于肠致病性大肠杆菌和肠出血性大肠杆菌（EPEC和EHEC）。也已鉴定出产志贺毒素的菌株。艾氏埃希菌的基因组特征，特别是与其他埃希菌属物种的差异，尚未得到很好的阐明。在此，我们对从多个来源分离的29株艾氏埃希菌菌株（3个完整序列和26个草图序列）进行了全基因组测序，并进行了种内和属内基因组比较。艾氏埃希菌基因组大小在4.5至5.1 Mb之间，比大肠杆菌菌株的基因组小。种内基因组比较确定了艾氏埃希菌的五个系统发育群。属内基因组比较显示，艾氏埃希菌的可能核心基因组由3250个基因组成，而埃希菌属的核心基因组由1345个基因组成。我们的分析进一步揭示了艾氏埃希菌的几个独特或显著的遗传特征，包括那些与已知生化特征和毒力因子相关的特征，以及一个可能活跃的被称为ETT2（大肠杆菌T3SS 2）的第二个T3SS，它在大肠杆菌中是失活的。尽管在体外观察到这种微生物不运动，但鞭毛生物合成基因是完全保守的；与趋化性相关的基因已被选择性删除。基于这些结果，我们开发了一种巢式聚合酶链反应系统来直接检测艾氏埃希菌。我们的数据定义了艾氏埃希菌的基因组特征，并为今后对这种重要的新出现肠道病原体的研究提供了有价值的基础。
