van der Staay G W, Moon-van der Staay S Y, Garczarek L, Partensky F
Observatoire Océanologique de Roscoff, CNRS-UPR 9042, Université Pierre et Marie Curie, BP 74, F-29682, Roscoff Cedex, France.
Photosynth Res. 2000;65(2):131-9. doi: 10.1023/A:1006445810996.
The nucleotide sequences of the genes coding for the subunits of the Photosystem I (PS I) core, PsaA and PsaB were determined for the marine prokaryotic oxyphototrophs Prochlorococcus sp. MED4 (CCMP1378), P. marinus SS120 (CCMP1375) and Synechococcus sp. WH7803. Divergence of these sequences from those of both freshwater cyanobacteria and higher plants was remarkably high, given the conserved nature of PsaA and PsaB proteins. In particular, the PsaA of marine prokaryotes showed several specific insertions and deletions with regard to known PsaA sequences. Even in between the two Prochlorococcus strains, which correspond to two genetically different ecotypes with shifted growth irradiance optima, the sequence identity was only 80.2% for PsaA and 88.9% for PsaB. Possible causes and implications of the fast evolution rates of these two PS I core subunits are discussed.
测定了海洋原核光合自养生物嗜盐绿球菌属MED4（CCMP1378）、海生嗜盐绿球菌SS120（CCMP1375）和聚球藻属WH7803中编码光系统I（PS I）核心亚基PsaA和PsaB的基因的核苷酸序列。鉴于PsaA和PsaB蛋白的保守性质，这些序列与淡水蓝细菌和高等植物的序列差异非常大。特别是，海洋原核生物的PsaA相对于已知的PsaA序列表现出几个特定的插入和缺失。即使在两种嗜盐绿球菌菌株之间，它们对应于两种具有不同生长辐照最佳值的遗传不同生态型，PsaA的序列同一性仅为80.2%，PsaB的序列同一性为88.9%。讨论了这两个PS I核心亚基快速进化速率的可能原因和影响。
