| Project/Area Number |
14560072
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
応用微生物学・応用生物化学
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| Research Institution | Kagawa University |
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Principal Investigator |
KIMURA Yoshio Kagawa University, Faculty of Agriculture, Professor, 農学部, 教授 (10243750)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEGAWA Kaoru Kagawa University, Faculty of Agriculture, Professor, 農学部, 教授 (50197282)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2002: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | cAMP / osmotic stress / Myxococcus xanthus / adenylyl cyclase / signal transduction / PKA / ホスホジエステラーゼ / 浸透圧センサー / M. xanthus / 粘液細菌 / 浸透圧ストレス / 情報伝達 |
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| Research Abstract |
Two adenylyl cyclase genes (cyaA and cyaB) were isolated from Myxococcus xanthus. The predicted cyaA and cyaB gene products had structural similarity to the receptor-type adenylyl cyclases that are composed of an amino-terminal sensor domain and a carboxy-terminal catalytic domain of adenylyl cyclase. A cyaA mutant, placed under condition of high-ionic (NaCl) or high-nonionic (sucrose) osmostress exhibited a marked reduction in spore formation and spore germination. In vegetative cells, cyaA mutant responded normally to osmotic stress. On the other hand, disruption of cyaB generates a mutant that showed growth retardation at high-ionic (NaCl) or high-nonionic (sucrose) osmolarity. Under nonionic osmostress, the cyaB mutant exhibited reduced spore germination, however, the germination rate of the cyaB mutant was significantly higher than that of the cyaA mutant. These results suggested that M. xanthus CyaA and CyaB function as osmosensors mainly during development and spore germination,
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and throughout the life cycle of M. xanthus including the vegetative stage, respectively.
Next, we isolated a clone from a M. xanthus genomic DNA library using oligonucleotide probes designed based on the conserved cAMP-binding domains of the cAMP-dependent protein kinase (PKA) regulatory subunits. The clone contained an open-reading frame, cbpB, encoding a hydrophilic protein with two cAMP-binding domains. The CbpB exhibited partial primary structural similarity to PKA regulatory subunits. cbpB mutant showed normal growth, development and spore germination. However, the cbpB mutant cultured under high- or low-temperature conditions exhibited a marked reduction in growth. cbpB mutant cells were also more sensitive to osmotic stress than wild-type cells. The phenotype of cbpB mutant was similar to those of PKA regulatory subunit mutants of some eukaryotic microorganisms. These results suggest that the cAMP-mediated signal transduction pathway plays an important role in osmotic and temperature adaptation in M. xanthus. The cAMP-mediated signal transduction pathway is not reported in bacteria. Less
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