Fitch W M, Bruschi M
Department of Biological Sciences, University of Southern California, Los Angeles 90089-1481.
Mol Biol Evol. 1987 Jul;4(4):381-94. doi: 10.1093/oxfordjournals.molbev.a040452.
Thirty-one bacterial type ferredoxins were examined by means of the parsimony method for their phylogenetic implications. The results show reasonable relationships in that photosynthetic, thermophilic, and desulfovibrio groups are identifiable; but a number of interesting anomalies occur. These include a methanogen sequence that clusters among the desulfovibrios. There are several differences from the phylogeny of Woese. At least two duplications producing paralogous genes are demonstrated, plus the probable existence of two more. The partial internal gene duplication that doubled the length of ferredoxin is confirmed by showing that the probability of the two ancestrally reconstructed halves possessing that much similarity by chance is 10(-7). Howard and co-workers proposed that the two halves of the Azotobacter vinelandii are reversed relative to most other sequences. A phylogeny, drawn with the halves of the azotobacter sequence (and its relatives) reversed produced a tree that had only three less nucleotide substitutions than did the tree without their halves reversed. This plus other evidence suggests that the significantly greater similarity observed across rather than within the halves is more likely the result of convergence.
采用简约法对31种细菌型铁氧化还原蛋白进行了研究，以探讨其系统发育意义。结果显示出合理的关系，即光合、嗜热和脱硫弧菌组是可识别的；但也出现了一些有趣的异常情况。其中包括一个产甲烷菌序列聚集在脱硫弧菌之中。与沃斯的系统发育存在一些差异。至少证明了有两次重复产生了旁系同源基因，另外可能还有两次。通过显示两个祖先重建的半段偶然具有如此高相似性的概率为10^(-7)，证实了使铁氧化还原蛋白长度加倍的部分内部基因重复。霍华德及其同事提出，相对于大多数其他序列，棕色固氮菌的两半是颠倒的。用棕色固氮菌序列（及其亲属）的两半颠倒后绘制的系统发育树，其核苷酸替换比两半未颠倒的树仅少三个。这一点以及其他证据表明，在两半之间而非内部观察到的显著更高的相似性更可能是趋同的结果。
