title: Re-characterization of an extrachromosomal circular plasmid in the pathogenic Leptospira interrogans serovar Lai strain 56601.
abstract: In China, Leptospira interrogans serovar Lai strain 56601 (str.56601) is one of main pathogenic strains that cause severe leptospirosis in both human and animals. The genome of this organism was completely sequenced in 2003. However, in 2011, we identified and corrected some assembly errors in the str.56601 genome due to the repeat sequences widely distributed in the Leptospira genome. In this study, we re-analyzed the previously reported mobile, phage-related genomic island in the chromosome and rectified detailed sequence information in both the plasmid and chromosome using various experimental methods. The presence of a separate circular extrachromosomal plasmid was also confirmed, and its location in the genomic region was determined relative to the genomic island reported in L. interrogans serovar Lai by a combination of pulsed-field gel electrophoresis -based and plasmid extraction-based Southern blot analysis. This report confirmed that the separate extrachromosomal circular plasmid is not integrated into the chromosome of L. interrogans str.56601 and markedly improved our understanding of the genomic organization, evolution, and pathogenesis of L. interrogans. In particular, characterization of this extrachromosomal circular plasmid will contribute to the development of genetic manipulation systems in pathogenic Leptospira species.
authors.affiliation: Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China.
authors.forename: Weinan
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China.
authors.forename: Ping
authors.initials: P
authors.lastname: He
authors.affiliation: Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China.
authors.forename: Xuran
authors.initials: X
authors.lastname: Zhuang
authors.affiliation: CAS-Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Guoping
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China.
authors.forename: Xiaokui
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China yzhzhu@hotmail.com jinhongqin@sjtu.edu.cn.
authors.forename: Jinhong
authors.initials: J
authors.lastname: Qin
authors.affiliation: Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China yzhzhu@hotmail.com jinhongqin@sjtu.edu.cn.
authors.forename: Yongzhang
authors.initials: Y
authors.lastname: Zhu
mesh_terms: D001483:Base Sequence; D002876:Chromosomes, Bacterial; D017931:DNA Primers; D007921:Leptospira interrogans / Q000235:genetics* / Q000472:pathogenicity; D010957:Plasmids
chemical_list: D017931:DNA Primers
keywords: Leptospira interrogans; extrachromosomal circular plasmid; genomic island