Department of Molecular Biology, University of Geneva, 1211, Geneva 4, Switzerland.
Plant Mol Biol. 1984 Nov;3(6):363-70. doi: 10.1007/BF00033383.
The region of the chloroplast genome of Chlamydomonas reinhardii containing the gene of the thylakoid polypeptide D2 (psbD) has been sequenced. A unique open reading frame of 350 codons exists in this region. Because the first ATG is followed 11 codons downstream by a second one, the D2 polypeptide consists of either 339 or 350 amino acids. Comparison of the sequences of D2 and the 32K dalton polypeptides, both of which are associated with photosystem II, reveals partial homology. Although, the overall homology of these two polypeptides is only 27%, they contain several related regions and their hydropathic profiles are strikingly similar. These data suggest that the two polypeptides may have related functions and/or that their genes may have originated from a common ancestor. Alternatively, convergent evolution of these polypeptides may be due to structural constraints in the thylakoid membrane. Limited sequence homology is also observed between the D2 polypeptide and some of the subunits of the reaction centers of photosynthetic bacteria.
已对莱茵衣藻叶绿体基因组中包含类囊体多肽 D2（psbD）基因的区域进行了测序。该区域存在一个独特的 350 个密码子的开放阅读框。由于第一个 ATG 下游 11 个密码子后紧跟着第二个 ATG，因此 D2 多肽由 339 或 350 个氨基酸组成。D2 和 32K 道尔顿多肽的序列比较表明它们具有部分同源性。尽管这两种多肽的整体同源性仅为 27%，但它们包含几个相关区域，其疏水性图谱非常相似。这些数据表明这两种多肽可能具有相关的功能，或者它们的基因可能来自共同的祖先。或者，这些多肽的趋同进化可能是由于类囊体膜中的结构限制所致。在 D2 多肽和光合细菌反应中心的一些亚基之间也观察到有限的序列同源性。
