Hwang S, Herrin D L
Botany Department, University of Texas, Austin 78713.
Curr Genet. 1993 May-Jun;23(5-6):512-7. doi: 10.1007/BF00312644.
A cDNA encoding the precursor to a major 20-kDa thylakoid polypeptide of Chlamydomonas reinhardtii (P22), previously localized to the photosystem I light-harvesting complex (LHCI), was characterized. N-terminal sequencing of P22 identified the precursor cleavage site. Genomic Southern blots and polymerase chain reaction analyses show that the gene for P22 (Lhca11) is single-copy and contains at least one intron. Northern-blot analyses show that Lhca11 mRNA is highly regulated in light-dark synchronized cells. The primary sequence and predicted topology of P22 has features characteristic of light-harvesting chlorophyll a/b-binding proteins from higher plants. Sequence comparisons indicate that P22 has significantly greater identity with the Type-I LHCI protein of tomato, compared to other LHC proteins. This result suggests that the divergence of LHCI proteins into the classes found in higher plants may have occurred early in evolution, prior to the separation of green algae and land plants.
对编码莱茵衣藻一种主要的20 kDa类囊体多肽前体（P22）的cDNA进行了表征，该多肽先前定位于光系统I捕光复合体（LHCI）。对P22进行N端测序确定了前体切割位点。基因组Southern杂交和聚合酶链反应分析表明，P22基因（Lhca11）是单拷贝的，且含有至少一个内含子。Northern杂交分析表明，Lhca11 mRNA在光暗同步细胞中受到高度调控。P22的一级序列和预测拓扑结构具有高等植物捕光叶绿素a/b结合蛋白的特征。序列比较表明，与其他LHC蛋白相比，P22与番茄的I型LHCI蛋白具有显著更高的同源性。这一结果表明，LHCI蛋白分化为高等植物中发现的类别可能发生在进化早期，即在绿藻和陆地植物分离之前。
