Hellborg Linda, Woolfit Megan, Arthursson-Hellborg Mattias, Piskur Jure
Cell and Organism Biology, Lund University, Lund, Sweden.
BMC Genomics. 2008 Apr 11;9:164. doi: 10.1186/1471-2164-9-164.
Genes continuously duplicate and the duplicated copies remain in the genome or get deleted. The DAL5 subfamily of transmembrane transporter genes has eight known members in S. cerevisiae. All are putative anion:cation symporters of vitamins (such as allantoate, nicotinate, panthotenate and biotin). The DAL5 subfamily is an old and important group since it is represented in both Basidiomycetes ("mushrooms") and Ascomycetes ("yeast"). We studied the complex evolution of this group in species from the kingdom of fungi particularly the Ascomycetes.
We identified numerous gene duplications creating sets of orthologous and paralogous genes. In different lineages the DAL5 subfamily members expanded or contracted and in some lineages a specific member could not be found at all. We also observed a close relationship between the gene YIL166C and its homologs in the Saccharomyces sensu stricto species and two "wine spoiler" yeasts, Dekkera bruxellensis and Candida guilliermondi, which could possibly be the result of horizontal gene transfer between these distantly related species. In the analyses we detect several well defined groups without S. cerevisiae representation suggesting new gene members in this subfamily with perhaps altered specialization or function.
The transmembrane DAL5 subfamily was found to have a very complex evolution in yeast with intra- and interspecific duplications and unusual relationships indicating specialization, specific deletions and maybe even horizontal gene transfer. We believe that this group will be important in future investigations of evolution in fungi and especially the evolution of transmembrane proteins and their specialization.
基因不断复制，复制后的拷贝会保留在基因组中或被删除。跨膜转运蛋白基因的DAL5亚家族在酿酒酵母中有八个已知成员。所有成员均可能是维生素（如尿囊酸、烟酸、泛酸和生物素）的阴离子：阳离子共转运体。DAL5亚家族是一个古老且重要的群体，因为在担子菌（“蘑菇”）和子囊菌（“酵母”）中均有代表。我们研究了该群体在真菌界尤其是子囊菌中的复杂进化。
我们鉴定出了大量基因复制事件，产生了直系同源基因和旁系同源基因集。在不同的谱系中，DAL5亚家族成员有所扩增或收缩，在某些谱系中根本找不到特定成员。我们还观察到基因YIL166C与其在狭义酿酒酵母物种以及两种“葡萄酒败坏菌”酵母（布鲁塞尔德克酵母和季也蒙念珠菌）中的同源物之间存在密切关系，这可能是这些远缘物种之间水平基因转移的结果。在分析中，我们检测到几个没有酿酒酵母代表的明确群体，表明该亚家族中有新的基因成员可能具有改变的专一性或功能。
发现跨膜DAL5亚家族在酵母中具有非常复杂的进化过程，包括种内和种间复制以及异常关系，表明存在专一化、特定缺失甚至可能的水平基因转移。我们认为该群体在未来真菌进化研究中，尤其是跨膜蛋白及其专一化进化研究中将具有重要意义。
