Molecular and global time-resolved analysis of a psbS genedosage effect on pH and xanthophyll cycle-dependent nonphotochemical quenching in photosystem 11
Date
2002
Authors
Li, Xiao-Ping
Gilmore, Adam
Niyogi, Krishna
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American Society for Biochemistry and Molecular Biology Inc
Abstract
Photosynthetic light harvesting in plants is regulated by a pH- and xanthophyll-dependent nonphotochemical quenching process (qE) that dissipates excess absorbed light energy and requires the psbS gene product. An Arabidopsis thaliana mutant, npq4-1, lacks qE because of a deletion of the psbS gene, yet it exhibits a semidominant phenotype. Here it is shown that the semidominance is due to a psbS gene dosage effect. Diploid Arabidopsis plants containing two psbS gene copies (wild-type), one psbS gene (npq4-1/NPQ4 heterozygote), and no psbS gene (npq4-1/npq4-1 homozygote) were compared. Heterozygous plants had 56% of the wild-type psbS mRNA level, 58% of the wild-type PsbS protein level, and 60% of the wild-type level of qE. Global analysis of the chlorophyll a fluorescence lifetime distributions revealed three components in wild-type and heterozygous plants, but only a single long lifetime component in npq4-1. The short lifetime distribution associated with qE was inhibited by more than 40% in heterozygous plants compared with the wild type. Thus, the extent of qE measured as either the fractional intensities of the PSII chlorophyll a fluorescence lifetime distributions or steady state intensities was stoichiometrically related to the amount of PsbS protein.
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Keywords: Chlorophyll; Fluorescence; Genes; Photosynthesis; Plants (botany); Quenching; Gene dosages; Biochemistry; chlorophyll a; gene product; messenger RNA; protein psbs; unclassified drug; xanthophyll; Arabidopsis; article; fluorescence; gene dosage; gene expre
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Journal of Biological Chemistry
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Journal article
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2037-12-31
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