期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1990
卷号：87
期号：11
页码：4038-4042
DOI：10.1073/pnas.87.11.4038
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Chlorophyll apoprotein accumulation in higher plant chloroplasts is controlled by light-dependent chlorophyll formation. Dark-grown plants lack chlorophyll and chlorophyll apoproteins. However, the plastid genes encoding the chlorophyll apoproteins are transcribed; chlorophyll apoprotein mRNA accumulates and associates with polysomes in plastids of dark-grown plants. Pulse-labeling assays revealed a population of short-lived proteins in plastids of dark-grown plants. One of these transiently labeled proteins was CP43, a chlorophyll apoprotein associated with photosystem II. Pulse-chase assays showed that newly synthesized CP43 was rapidly degraded in plastids of dark-grown plants, which lack chlorophyll. In contrast, CP43 synthesized in plastids from illuminated plants was stable. The synthesis of D1, a chlorophyll apoprotein of the photosystem II reaction center, was also analyzed in plastids of dark-grown and illuminated plants. Radiolabel accumulation into full-length D1 was only detected in plastids of illuminated plants. However, D1 translation intermediates of 15-25 kDa were detected in both plastid populations. Pulse-chase assays showed that the 15- to 25-kDa D1 translation products were precursors of mature D1 in plastids of illuminated plants. In contrast, in plastids of dark-grown plants, the 15- to 25-kDa translation intermediates were converted into a 23-kDa polypeptide previously suggested to be a proteolytic product of D1. These results indicate that chlorophyll produced in illuminated plants stabilizes D1 nascent polypeptides, which allows accumulation of mature D1.
