Fish L E, Jagendorf A T
Plant Biology Section, Cornell University, Ithaca, New York 14853.
Plant Physiol. 1982 Apr;69(4):814-24. doi: 10.1104/pp.69.4.814.
Within 8 to 10 minutes of illumination, chloroplast thylakoids of pea (Pisum sativum) became enriched 30 to 100% in ribosomes bound by nascent chains. Following (or, in some experiments, coincident with) this apprarent redistribution was a 25 to 65% increase in the total bound ribosome population, which was then maintained at this higher level during the normal light period. On transfer of plants to darkness, the bound ribosome population decreased to the lower dark level. White, blue (400 to 520 nanometers), and orange (545 to 690 nanometers) light were all effective in producing an increase in the bound ribosome population. The level of bound ribosomes in the oldest leaves of 16-day-old plants was 15-fold less than in the still-maturing leaf but was still increased by illumination.In vivo experiments with chloramphenicol and lincomycin indicated a requirement for protein synthesis by the 70S ribosomes both for the light-induced shift to the population bound by nascent chains and for the increase in the total thylakoid-bound population. When thylakoids from plants in darkness or exposed to light for increasing periods were incubated in an Eschericia coli cell-free protein synthesizing system, 15 minutes of prior illumination in vivo produced a 60% increase in [(3)H]leucine incorporation. This stimulation preceded the increase in total bound ribosomes but corresponded in time to observed increases in the ribosomes bound by nascent chains.A light intensity of 100 micromoles per meter(2) per second, but not 25 micromoles per meter(2) per second, caused a significant increase in bound ribosomes over a 30-minute period. Strong inhibition in vivo by 3',4'-dichlorophenyl-1, 1-dimethylurea suggests that noncyclic electron flow is essential for light-induced ribosome redistribution.
在光照8至10分钟内，豌豆（Pisum sativum）叶绿体类囊体中与新生链结合的核糖体富集了30%至100%。在此明显的重新分布之后（或在某些实验中，与之同时），结合核糖体的总数增加了25%至65%，然后在正常光照期间维持在这个较高水平。将植物转移到黑暗中后，结合核糖体的数量下降到较低的黑暗水平。白光、蓝光（400至520纳米）和橙光（545至690纳米）都能有效地使结合核糖体的数量增加。16日龄植物最老叶片中的结合核糖体水平比仍在成熟的叶片低15倍，但仍能因光照而增加。用氯霉素和林可霉素进行的体内实验表明，70S核糖体进行蛋白质合成对于光诱导向与新生链结合的核糖体群体转变以及类囊体结合总数的增加是必需的。当将黑暗中或暴露于光照不同时长的植物的类囊体在大肠杆菌无细胞蛋白质合成系统中孵育时，体内预先15分钟的光照使[³H]亮氨酸掺入量增加了60%。这种刺激在结合核糖体总数增加之前出现，但在时间上与观察到的与新生链结合的核糖体增加相对应。每秒100微摩尔每平方米的光强，但不是每秒25微摩尔每平方米的光强，在30分钟内导致结合核糖体显著增加。3',4'-二氯苯基-1,1-二甲基脲在体内的强烈抑制作用表明，非循环电子流对于光诱导的核糖体重新分布至关重要。
