Role of selfish restriction-modification gene complexes in genome evolution : comparative genomics and experimental evolution
Grant-in-Aid for Scientific Research (B)
|Allocation Type||Single-year Grants|
|Research Institution||The University of Tokyo|
KOBAYASHI Ichizo The University of Tokyo, Department of Medical Genome Sciences, Graduate School of Frontier Science, Professor, 大学院・新領域創成科学研究科, 教授 (30126057)
|Project Period (FY)
2003 – 2004
Completed(Fiscal Year 2004)
|Budget Amount *help
¥15,300,000 (Direct Cost : ¥15,300,000)
Fiscal Year 2004 : ¥7,400,000 (Direct Cost : ¥7,400,000)
Fiscal Year 2003 : ¥7,900,000 (Direct Cost : ¥7,900,000)
|Keywords||comparative genomics / genome evolution / bacterial genome / genome rearrangement / pathogenic bacteria / systems biology / restriction enzyme / epigenetics / ゲノム / 遺伝子増幅 / 進化生態 / 大腸菌 / 枯草菌 / 最近 / バイオテクノロジー / 利己的遺伝子|
1.Conditions for post-segregational host killing (genetic addiction)
We found that EcoRI modification enzyme is as stable as EcoRI restriction enzyme and bulk cellular proteins. We analyzed conditions for evolution of addiction genes using evolutionary ecology approach. Importance of space structure was demonstrated.
2.Restriction enzyme and modification enzyme obtained through comparative genomics with hyperthermophilic archaea
Through comparison of the genomes of Pyrococcus abyssi and Pyrococcus horikoshii, we identified a putative restriction-modification gene complex inserted into the former genome. We identified restriction enzyme PabI through expression screening in wheat germ-derived cell-free protein synthesis system. It generates a novel terminus TA3' at 5'GTAC.
3.Reconstruction of formation of large genome polymorphisms through comparison of closely-related genomes
Comparing 7 genomes of Staphylococcus aureus, we found evolution of S (specificity) subunit of Type I restriction enz
yme through combination of two target recognition domains. From analysis of three tandem paralogue gene clusters, we concluded that some genome rearrangments have resulted from homologous recombination between sequence within each unit conserved for its functional importance. Comparing 4 genomes of Neisseria, we identified filamentous phages likely integrated by its transposase and occasionally rearranged by it.
4.DNA breakage and genome rearrangements triggered by restriction breaks and others
We found that Type III restriction breakage after single infection of bacteriophage lambda is repaired by homologous recombination function of prophage. Homology-driven illegitimate recombination was found to depend on RecA and Type I restriction sites. We developed a sensitive assay of linearization of circular bacterial chromosome and analyzed various recombination-defective mutants of E.coli. We demonstrated high level of DNA double-strand break repair in BJ5183 strain of E.coli. We modeled asymmetric branch migration of Holliday structure and analyzed data in vitro.
5.Multiplication of a restriction-modification gene complex
We showed that tandem amplification of BamHI restriction-modification gene complex on Bacillus subtilis chromosome is dependent on function of the restriction enzyme. Less
Research Products (59results)