Real-Time Evolution of a Subtelomeric Gene Family in Candida albicans.
Real-Time Evolution of a Subtelomeric Gene Family in Candida albicans.
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DOI：
10.1534/genetics.115.177451
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发表时间：
2015-07
期刊：
影响因子：
3.3
通讯作者：
Berman J
中科院分区：
文献类型：
--
作者：
Anderson MZ;Wigen LJ;Burrack LS;Berman J
基因组的亚端粒区域以高速率的序列进化和快速的基因更新而闻名。亚端粒进化的证据在很大程度上依赖于历史进化模式的比较，以推断这些事件的趋势和频率。在这里，我们描述了在实验室传代超过4000代的白色念珠菌亚端粒TLO基因家族的演变。C.白色念珠菌是人类的寄生性和机会性病原体，TLO基因家族编码调节转录并影响一系列毒力因子的介体复合物的亚基。我们确定了16个不同的亚端粒重组事件，改变了TLO剧目。不同染色体末端的亚端粒之间的异位重组大约每5000代发生一次，并且通常随后发生杂合性丢失，导致一个TLO基因序列的完全丢失和另一个TLO基因序列的扩增。在一种情况下，TLO基因内的重组产生了新的TLO基因序列。TLO拷贝数的变化是有偏差的，一些TLO优先被复制到新的染色体臂和其他TLO基因经常丢失。这些非相互重组事件中的大多数发生在TLO编码序列的3′端或TLO编码序列的着丝粒近端的保守的50-bp序列元件内。因此，亚端粒重组是通过改变相关基因家族成员的数量和序列来产生基因型多样性的快速机制。
Subtelomeric regions of the genome are notable for high rates of sequence evolution and rapid gene turnover. Evidence of subtelomeric evolution has relied heavily on comparisons of historical evolutionary patterns to infer trends and frequencies of these events. Here, we describe evolution of the subtelomeric TLO gene family in Candida albicans during laboratory passaging for over 4000 generations. C. albicans is a commensal and opportunistic pathogen of humans and the TLO gene family encodes a subunit of the Mediator complex that regulates transcription and affects a range of virulence factors. We identified 16 distinct subtelomeric recombination events that altered the TLO repertoire. Ectopic recombination between subtelomeres on different chromosome ends occurred approximately once per 5000 generations and was often followed by loss of heterozygosity, resulting in the complete loss of one TLO gene sequence with expansion of another. In one case, recombination within TLO genes produced a novel TLO gene sequence. TLO copy number changes were biased, with some TLOs preferentially being copied to novel chromosome arms and other TLO genes being frequently lost. The majority of these nonreciprocal recombination events occurred either within the 3′ end of the TLO coding sequence or within a conserved 50-bp sequence element centromere-proximal to TLO coding sequence. Thus, subtelomeric recombination is a rapid mechanism of generating genotypic diversity through alterations in the number and sequence of related gene family members.