Untitled - 中国植物生理与分子生物学学会

THE EFFECT OF THYLAKOID FORMATION 1 ON LHCII
TRIMERIZATION MEDIATED BY PsbS, WHICH WAS
INVOLVED IN OCCURRENCE OF VARIEGATION IN
ARABIDOPSIS THALIANA
Lingang Zhang, Yuxiang Cheng, Jirong Huang
National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology,
Shanghai Institutes for Biological Science, Chinese Academy of Sciences, 200032 Shanghai,
People's Republic of China
Deletion of THYLAKOID FORMATION 1 (THF1) gene results in variegated leaves, where
chloroplast development is impaired in yellow sectors while appears normal in green sectors.
Previous studies suggested that occurrence of variegated leaves was not due to problems in
thylakoid membrane formation, but rather to light-induced damage resulting from uncoupled
antenna proteins of photosystem II (PSII). In our experiments, the results of Blue Native PAGE
indicated that aggregate formation of light harvesting complex II (LHCII) of thf1 mutant was
changed significantly, LHCII trimer decreased and monomer increased. The conversion from
trimer to monomer decreased ability of nophotochemical quenching (NPQ), which can dissipate
excess energy absorbed by PSII. The results of co-localization, co-immunoprecipitation and
pull-down experiments suggested that THF1 can interact with PsbS in vivo and in vitro. LHCII
trimer also decreased in npq4 mutant implied that monomerization of LHCII trimer in thf1
mutant was mediated by PsbS. So, monomerizaion of LHCII trimer in thf1 reduced NPQ of
PSII, which can not efficiently protect PSII reaction center from photodamage that ever been
thought as a prerequisite of variegation of Arabidopsis.
Keywords:Arabidopsis; Thylakoid formation 1 (THF1); photosystem II (PSII); LHCII trimer
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