Department of Biochemistry and Molecular Biology, Wayne State University, School of Medicine, Detroit, MI 48201, USA.
Mol Plant. 2011 Jan;4(1):42-58. doi: 10.1093/mp/ssq040. Epub 2010 Oct 15.
Land plants and algae form a supergroup, the Archaeplastida, believed to be monophyletic. We report the results of an analysis of the phylogeny of putative globins in the currently available genomes to bacterial and other eukaryote hemoglobins (Hbs). Archaeplastida genomes have 3/3 and 2/2 Hbs, with the land plant genomes having group 2 2/2 Hbs, except for the unexpected occurrence of two group 1 2/2 Hbs in Ricinus communis. Bayesian analysis shows that plant 3/3 Hbs are related to vertebrate neuroglobins and bacterial flavohemoglobins (FHbs). We sought to define the bacterial groups, whose ancestors shared the precursors of Archaeplastida Hbs, via Bayesian and neighbor-joining analyses based on COBALT alignment of representative sets of bacterial 3/3 FHb-like globins and group 1 and 2 2/2 Hbs with the corresponding Archaeplastida Hbs. The results suggest that the Archaeplastida 3/3 and group 1 2/2 Hbs could have originated from the horizontal gene transfers (HGTs) that accompanied the two generally accepted endosymbioses of a proteobacterium and a cyanobacterium with a eukaryote ancestor. In contrast, the origin of the group 2 2/2 Hbs unexpectedly appears to involve HGT from a bacterium ancestral to Chloroflexi, Deinococcales, Bacilli, and Actinomycetes. Furthermore, although intron positions and phases are mostly conserved among the land plant 3/3 and 2/2 globin genes, introns are absent in the algal 3/3 genes and intron positions and phases are highly variable in their 2/2 genes. Thus, introns are irrelevant to globin evolution in Archaeplastida.
陆地植物和藻类形成了一个超类群，即古生菌，被认为是单系的。我们报告了对当前可用基因组中假定球蛋白系统发育的分析结果，这些基因组与细菌和其他真核生物血红蛋白（Hbs）进行了比较。古生菌基因组有 3/3 和 2/2 Hbs，陆地植物基因组有 2/2 组 2 Hbs，但蓖麻意外地出现了两个组 1 2/2 Hbs。贝叶斯分析表明，植物 3/3 Hbs与脊椎动物神经球蛋白和细菌黄素血红蛋白（FHbs）有关。我们试图通过基于 COBALT 对齐的代表细菌 3/3 FHb 样球蛋白和组 1 和 2 2/2 Hbs 的贝叶斯和邻接聚类分析，定义细菌群，其祖先与古生菌 Hbs 的前体共享，与相应的古生菌 Hbs 进行比较。结果表明，古生菌 3/3 和组 1 2/2 Hbs 可能起源于水平基因转移（HGT），这些转移伴随着与真核生物祖先的一种变形杆菌和一种蓝细菌的两次普遍接受的内共生作用。相比之下，组 2 2/2 Hbs 的起源出乎意料地涉及到从绿弯菌门、栖热菌目、芽孢杆菌和放线菌的细菌祖先的 HGT。此外，尽管陆地植物 3/3 和 2/2 球蛋白基因的内含子位置和相位大多是保守的，但藻类 3/3 基因中没有内含子，而它们的 2/2 基因中的内含子位置和相位高度可变。因此，内含子与古生菌的球蛋白进化无关。
