2002 Fiscal Year Final Research Report Summary
Roles of restriction-modification gene complexes in generation of genome diversity in bacteria
| Project/Area Number |
12470034
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Pathological medical chemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KOBAYASHI Ichizo The University of Tokyo, Institute of Medical Science, Associate Professor, 医科学研究所, 助教授 (30126057)
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| Co-Investigator(Kenkyū-buntansha) |
UCHIYAMA Ikuo National Institutes of Natural Sciences, National Institute for Basic Biology, Research Associate, 基礎生物学研究所, 助手 (90243089)
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| Project Period (FY) |
2000 – 2002
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| Keywords | pathogenic bacteria / bacterial genomes / genome polymorphism / genome instability / genome evolution / genome comparison / pathogenicity / toxin |
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| Research Abstract |
A. Experimental analyses of genome dynamics.
(A-1) Multiplication of a restriction-modification gene complex.
Here we found amplification of a restriction-modification gene complex. BamHI gene complex inserted into Bacillus chromosome showed resistance to replacement by a homologous stretch of DNA. The multiplication takes place in a bacterium with natural capacity for DNA release, uptake and transformation and might contribute to spreading of RM gene complexes in a virus like life cycle.
(A-2) Intragenomic movement of a restriction-modification gene complex.
We detected movement of a restriction-modification gene complex within a cell when attempts were made to eliminate it from the cell. From sequence determination of these products, we discussed mechanisms of the underlying cooperation between restriction-modification gene complexes, IS and host homologous recombination functions.
(A-3) Defense of genomes against attack by restriction-modification systems.
We demonstrated that host attack
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by EcoRII restriction-modification gene complex can be counteracted by Dcm solitary methyltransferase. We also found that site-specific recombination machinery in the chromosome can defend the genome against attack by a restriction-modification system.
B. Comparison and informatic analysis of closely related bacterial genomes.
(B-1) Staphylococcus aureus.
We compared genome sequences of two strains of S. aureus. We listed medium-sized genome polymorphisms and inferred mechanisms of their formation. We identified restriction-modification gene homologues in S. hominis.
(B-2) Neisseria.
We compared genomes sequences of two strains of N. meningitides and one strain of N. gonorhoeae and identified genome rearrangement mechanisms related to IS and restriction-modification gene complexes.
(B-3) Development of tools for genome comparison.
We developed a tool for comparison of closely-related genomes.
C. A new nomenclature for restriction modification enzymes and their genes.
We proposed a new system of nomenclature of restriction enzymes methyltransferases and their genes based on their biological diversity. Less
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