1994 Fiscal Year Final Research Report Summary
Molecular characterization of flagellar regulons in strains of the genus Shigella
Project/Area Number |
05640694
|
Research Category |
Grant-in-Aid for General Scientific Research (C)
|
Allocation Type | Single-year Grants |
Research Field |
遺伝
|
Research Institution | Faculty of Science, Okayama University |
Principal Investigator |
ENOMOTO Masatoshi Faculty of Science, Okayama University Professor, 理学部, 教授 (40000236)
|
Project Period (FY) |
1993 – 1994
|
Keywords | Four Shigella species / Cryptic flagellar regulon / Cryptic flagellin genes / fliC nucleotide sequences / fliC operator sequence / fliC repression / Gene rearrangement / Lateral gene transfer |
Research Abstract |
Cryptic flagellin genes, fliC,were detected in strains of the genus Shigella. The fliC genes cloned from S.flexneri, S.boydii and S.sonnei conferred motility on a nonmotile E.coli fliC mutant, while that from S.dysenteriae was nonfunctional. The fliC genes from two S.sonnei strains were repressed their expression in the E.coli fliC mutant when the fliA gene, a repressor gene involved in flagellar phase variation of Salmonella, was previously transformed into the host. Genes or their remnants involved in phase variation were not detected in S.sonnei. Nucleotide sequences of the fliC genes from the four species all consisted of the 5'-constant, central variable, and 3'-constant regions like the E .coli and Salm. typhimurium fliC genes. The 5'-and 3'-constant sequences and the control sequences of the upstream and downstream regions of the fliC genes from the three species but S.sonnei were highly homologous to those of E.coli although an IS1-insertion mutation was detected in the S.dysenteriae fliC gene.However, the upstream sequences of the two S.sonnei fliC genes were almost identical to that of the Salm. typhimurium fliC gene, suggesting that this sequence contains the operator site recognizable by Salmonella FljA repressor and has been laterally transferred from some Salmonella species in the past. Comparison of the constant sequences between the two S.sonnei fliC genes suggested that Shigella species had lost their motility at most 10^5 years ago. Likewise, comparison among the central variable sequences of the fliC genes from E.coli, Salm. typhimurium and four Shigella species suggested that these three genera had shared a common ancestor 80 million years ago.Further analysis with four different S.dysenteriae strains showed that this species has undergone severe gene rearrangement and lateral gene transfer from other Shigella species.
|
Research Products
(6 results)