1993 Fiscal Year Final Research Report Summary
Study of cAMP-dependent signal transduction system in algae
| Project/Area Number |
03454008
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
植物生理学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
OHMORI Masayuki College of Arts and Sciences, The University of Tokyo, Professor, 教養学部, 教授 (80013580)
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| Project Period (FY) |
1991 – 1993
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| Keywords | cyanobacterium / adenylate cyclase / cAMP / Anabaena / Spirulina / amino acid |
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| Research Abstract |
The cellular level of cyclic 3', 5'-AMP (cAMP) in the cyanobacterium Anabaena cylindrica changed transiently in response to changes in extracellular environments. When the cells were transferred from dark to light, or anaerobic to aerobic conditions in the dark, the cAMP level rapidly decreased within one min and then gradually recovered. It is suggested that the changes in membrane electrochemical potential is involved in the regulation of cellular cAMP concentration. Adenylate cyclase activity was detected in Spirulina platensis and Anabaena cylindrica but not in Synechocystis. There was a good correlation between the concentration of cellular cAMP and the activity of the enzyme.
A dense suspension of Spirulina platensis trichomes aggregated rapidly and formed a diskshaped algal mat when cAMP was added. Cyclic AMP significantly stimulated algal mat formation at concentration as low as 10^<-7>M.Stimulation of the mat formation was most rapid at about 10^<-5>M cAMP, but higher concentrations were not increasingly effective. Other nucleotides such as cGMP, ATP and AMP showed no stimulatory effect on algal mat formation.
By complementation of cya mutation in E.coli, we have isolated adenylate cyclase(cya) gene from cyanobacterium Anabaena cylindrica and determined the complete nucleotide sequence. The gene encodes a polipeptide consisting of 502 amino acid residues.
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