1994 Fiscal Year Final Research Report Summary
Studies of diversification of plasmid replication regions by genetic recombination
| Project/Area Number |
04454001
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
遺伝学
|
|---|
| Research Institution | University of Electro-Communications |
|---|
Principal Investigator |
MIZOBUCHI Kiyoshi University of Electro-Communications, Faculty of Electro-Communications, Professor, 電気通信学部, 教授 (00092346)
|
|---|
| Project Period (FY) |
1992 – 1994
|
| Keywords | IncIalpha and IncFII plasmids / replication region / diversification / reciprocal recombination / RNA structures / Replication control / RNAの高次構造 |
|---|
| Research Abstract |
Living things are information systems that are highly organized by a variety of genes. In this project, we have studied how replication systems of some bacterial plasmids diverged during the course of evolution. The basic replicons of bacterial plasmids consist of two sets of genetic systems, the replication-structural system and the replication control system. Comparison of nucleotide sequences suggested that plasmids P307 (IncFI) and pMU2200 (IncZ) were generated by reciprocal recombination between ancestors of R100 (IncFII) and ColIb-P9 (IncIalpha) , or vice versa. The plasmids of each pair, P307/pMU2200 and R100/ColIb-P9, are structurally unrelated to each other. Based on this information, we constructed in vitro and analyzed P307-like chimeric replicons from ColIb-P9 and R100. When the replication-structural region of ColIb-P9 was combined with the whole replication control region of R100, the resultant replicon replicated stably as R100 did. These results revealed that the basic replicons of the plasmids diverged by exchanging their replication control systems. Thus, we propose that the replication control systems of plasmids, in some cases, evolved independently of their structural systems, although these two systems work together for maintaining the replication functions. We also studied that the reciprocal recombination was specified by the unique secondary structures of RNA involved in the control of expression of the genes encoding the replication initiator proteins.
|
