Calcium and calmodulin are involved in blue light induction of the gsa gene for an early chlorophyll biosynthetic step in Chlamydomonas

The Chlamydomonas reinhardtii nuclear gene gsa, which encodes the early chlorophyll biosynthetic enzyme glutamate 1-semialdehyde aminotransferase (GSAT), is specifically induced by blue light in cells synchronized in a 12-hr-light and 12-hr-dark regime. Light induction required the presence of a nit...

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Bibliographic Details
Published in:The Plant cell 1996-12, Vol.8 (12), p.2245-2253
Main Authors: Im, G.S. (Brown University, Providence, RI.), Matters, G.L, Beale, S.I
Format: Article
Language:English
Subjects:
Acetates
Acetates - metabolism
Acetates - pharmacology
ACIDE ACETIQUE
ACIDO ACETICO
AMINOTRANSFERASAS
AMINOTRANSFERASE
AMMONIAC
AMONIACO
Animals
ANTIMETABOLITE
ANTIMETABOLITOS
ARN MENSAJERO
ARN MESSAGER
CALCIO
CALCIUM
Calcium - metabolism
Calcium - pharmacology
Calcium Channel Blockers - pharmacology
Calmodulin - metabolism
CALMODULINA
CALMODULINE
CATION
CATIONES
CHLAMYDOMONAS REINHARDTII
Chlamydomonas reinhardtii - drug effects
Chlamydomonas reinhardtii - genetics
Chlamydomonas reinhardtii - metabolism
Chlorophyll - biosynthesis
Chlorophylls
Enzyme Induction - drug effects
EXPRESION GENICA
EXPRESSION DES GENES
Gels
GENE
GENES
Genes, Plant
GENETICA
GENETIQUE
Intramolecular Transferases
Isomerases - biosynthesis
Light
LUMIERE
LUZ
Magnesium - pharmacology
Messenger RNA
METABOLISME
METABOLISMO
Neodymium - pharmacology
Nifedipine - pharmacology
NITRATE
NITRATOS
Nitrogen
Plant cells
Plants
RNA
Signal transduction
Sulfonamides - pharmacology
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Summary:The Chlamydomonas reinhardtii nuclear gene gsa, which encodes the early chlorophyll biosynthetic enzyme glutamate 1-semialdehyde aminotransferase (GSAT), is specifically induced by blue light in cells synchronized in a 12-hr-light and 12-hr-dark regime. Light induction required the presence of a nitrogen source in the incubation medium. Maximal induction also required acetate. However, in the absence of acetate, partial induction occurred when Ca2+ was present in the medium at concentrations of greater than or equal to 1 micromolar. The Ca2+ channel-blocking agents Nd3+ and nifedipine partially inhibited the external Ca2+-supported induction of GSAT mRNA but did not inhibit acetate-supported induction. The calmodulin antagonists trifluoperazine and N-(6-aminohexyl)-5-chloro 1-naphthalenesulfonamide inhibited both external Ca2+-supported and acetate-supported induction. The Ca2+ ionophore A23187 caused a transient induction in the dark. These results suggest that Ca2+ and calmodulin are involved in the signal transduction pathway linking blue light perception to the induction of GSAT mRNA. The electron transport uncoupler carbonyl cyanide m-chlorophenylhydrazone inhibited acetate-supported induction of GSAT mRNA but did not inhibit external Ca2+-supported induction. It is proposed that in the presence of acetate, an internal pool of Ca2+ can be mobilized as a second message, whereas in the absence of acetate, internal Ca2+ is not available but the requirement for Ca2+ can be partially met by an external Ca2+ source. The mobilization of internal Ca2+ may require energy derived from metabolism of acetate
ISSN:1040-4651
1532-298X
DOI:10.1105/tpc.8.12.2245