Low-light-adapted Prochlorococcus species possess specific antennae for each photosystem
Low-light-adapted Prochlorococcus species possess specific antennae for each photosystem
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DOI：
10.1038/nature01933
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发表时间：
2003-08-28
期刊：
影响因子：
64.8
通讯作者：
Barber, J
中科院分区：
文献类型：
--
作者：
Bibby, TS;Mary, I;Barber, J
原绿球藻是光合生物中最丰富的属（1），其在海洋中的深度分布非常广泛，这是因为它们具有适应低光或强光生态位的不同基因型（2，3）。pcb基因编码该属中主要的叶绿素结合、捕光天线蛋白（4），在低光菌株中以多个拷贝存在，但在高光菌株中以单个拷贝存在（5）。然而，这种区分的基础仍然模糊不清。在这里，我们表明，中度低光适应菌株原绿球藻属MIT 9313具有一个铁胁迫诱导的pcb基因，其编码用于光系统I（PSI）的天线蛋白-与来自蓝细菌的isiA基因相当（6，7）-和组成型表达的pcb基因，其编码光系统II（PSII）天线蛋白。通过比较，非常低光适应的菌株SS 120具有编码组成型PSI和PSII触角的七个pcb基因，加上一个PSI铁调节的pcb基因，而高光适应的菌株MED 4仅具有组成型PSII触角。因此，似乎原绿球藻对低光环境的适应已经引发了Pcb蛋白的增殖和特化，其与在植物和绿色藻类中发现的Cab蛋白相当（8）。
Prochlorococcus, the most abundant genus of photosynthetic organisms(1), owes its remarkably large depth distribution in the oceans to the occurrence of distinct genotypes adapted to either low- or high-light niches(2,3). The pcb genes, encoding the major chlorophyll-binding, light-harvesting antenna proteins in this genus(4), are present in multiple copies in low- light strains but as a single copy in high-light strains(5). The basis of this differentiation, however, has remained obscure. Here we show that the moderate low- light-adapted strain Prochlorococcus sp. MIT 9313 has one iron-stress-induced pcb gene encoding an antenna protein serving photosystem I (PSI)-comparable to isiA genes from cyanobacteria(6,7) -and a constitutively expressed pcb gene encoding a photosystem II (PSII) antenna protein. By comparison, the very low- light-adapted strain SS120 has seven pcb genes encoding constitutive PSI and PSII antennae, plus one PSI iron-regulated pcb gene, whereas the high-light-adapted strain MED4 has only a constitutive PSII antenna. Thus, it seems that the adaptation of Prochlorococcus to low light environments has triggered a multiplication and specialization of Pcb proteins comparable to that found for Cab proteins in plants and green algae(8).