The psbA gene family in cyanobacteria encodes different forms of the D1 protein that is part of the Photosystem II reaction centre. We have identified a phylogenetically distinct D1 group that is intermediate between previously identified G3-D1 and G4-D1 proteins (Cardona et al. Mol Biol Evol 32:1310–1328, 2015). This new group contained two subgroups: D1^INT, which was frequently in the genomes of heterocystous cyanobacteria and D1^FR that was part of the far-red light photoacclimation gene cluster of cyanobacteria. In addition, we have identified subgroups within G3, the micro-aerobically expressed D1 protein. There are amino acid changes associated with each of the subgroups that might affect the function of Photosystem II. We show a phylogenetically broad range of cyanobacteria have these D1 types, as well as the genes encoding the G2 protein and chlorophyll f synthase. We suggest identification of additional D1 isoforms and the presence of multiple D1 isoforms in phylogenetically diverse cyanobacteria supports the role of these proteins in conferring a selective advantage under specific conditions.

蓝细菌中的psbA基因家族编码不同形式的D1蛋白，该蛋白是Photosystem II反应中心的一部分。我们已经鉴定出一个系统发育独特的D1组，该组介于先前鉴定的G3-D1和G4-D1蛋白之间（Cardona等人，Mol Biol Evol 32：1310–1328，2015）。这个新的组包含两个亚组：D1 ^INT和D1 ^FR，D1 ^INT经常出现在异型蓝藻细菌的基因组中这是蓝细菌的远红光光适应基因簇的一部分。此外，我们已经确定了G3内的亚组，这是微需氧表达的D1蛋白。与每个亚组相关的氨基酸变化都可能影响光系统II的功能。我们显示，在系统发育上，蓝细菌具有这些D1类型，以及编码G2蛋白和叶绿素f合酶的基因。我们建议鉴定其他D1同工型，以及系统发育多样的蓝细菌中多个D1同工型的存在，支持这些蛋白在特定条件下赋予选择性优势的作用。