Stassen N Y, Logsdon J M, Vora G J, Offenberg H H, Palmer J D, Zolan M E
Department of Biology, Indiana University, Bloomington, IN 47405, USA.
Curr Genet. 1997 Feb;31(2):144-57. doi: 10.1007/s002940050189.
In eubacteria, the recA gene has long been recognized as essential for homologous recombination and DNA repair. Recent work has identified recA homologs in archaebacteria and eukaryotes, thus emphasizing the universal role this gene plays in DNA metabolism. We have isolated and characterized two new recA homologs, one from the basidiomycete Coprinus cinereus and the other from the angiosperm Lycopersicon esculentum. Like the RAD51 gene of Saccharomyces cerevisiae, the Coprinus gene is highly induced by gamma irradiation and during meiosis. Phylogenetic analyses of eukarotic recA homologs reveal a gene duplication early in eukaryotic evolution which gave rise to two putatively monophyletic groups of recA-like genes. One group of 11 characterized genes, designated the rad51 group, is orthologous to the Saccharomyces RAD51 gene and also contains the Coprinus and Lycopersicon genes. The other group of seven genes, designated the dmc1 group, is orthologous to the Saccharomyces DMC1 gene. Sequence comparisons and phylogenetic analysis reveal extensive lineage- and gene-specific differences in rates of RecA protein evolution. Dmc1 consistently evolves faster than Rad51, and fungal proteins of both types, especially those of Saccharomyces, change rapidly, particularly in comparison to the slowly evolving vertebrate proteins. The Drosophila Rad51 protein has undergone remarkably rapid sequence divergence.
在真细菌中，recA基因长期以来一直被认为是同源重组和DNA修复所必需的。最近的研究在古细菌和真核生物中鉴定出了recA同源物，从而强调了该基因在DNA代谢中所起的普遍作用。我们已经分离并鉴定了两个新的recA同源物，一个来自担子菌灰盖鬼伞，另一个来自被子植物番茄。与酿酒酵母的RAD51基因一样，灰盖鬼伞的基因在γ射线照射和减数分裂期间会被高度诱导。对真核生物recA同源物的系统发育分析表明，在真核生物进化早期发生了一次基因复制，产生了两个推测为单系的recA样基因群。一组有11个已鉴定的基因，称为rad51组，与酿酒酵母的RAD51基因直系同源，也包含灰盖鬼伞和番茄的基因。另一组有7个基因，称为dmc1组，与酿酒酵母的DMC1基因直系同源。序列比较和系统发育分析揭示了RecA蛋白进化速率中广泛的谱系和基因特异性差异。Dmc1的进化始终比Rad51快，两种类型的真菌蛋白，尤其是酿酒酵母的蛋白，变化迅速，特别是与进化缓慢的脊椎动物蛋白相比。果蝇的Rad51蛋白经历了非常快速的序列分化。
