酿酒酵母rDNA的结构及其介导整合影响因素研究进展

Review of the rDNA Structure and the Influence Factors for rDNA-Mediated Integration in Saccharomyces cerevisiae

为提高外源基因在酿酒酵母基因组中的拷贝数,将rDNA重复序列作为整合载体同源重组位点的研究日益被关注.本文介绍了酿酒酵母rDNA组成元件的结构,综述了以rDNA重复序列作为同源重组位点的研究进展.分析表明,hot1片段和一些蛋白因子(Fob1,RAD52和MRX,Sir2p,Sgs1和Mus81等)对rDNA单元的拷贝数目有调控作用,Smc5-Smc6复合体、RAD52的SUMO化和Mms21对rDNA的同源重组严格调控,对其稳定性有重要影响.以rDNA介导整合的外源基因在酿酒酵母细胞有丝分裂中的稳定性与整合位点在rDNA单元中的位置和性质以及整合载体的大小有重要关系.根据酿酒酵母较易发生同源重组的特点,使用rDNA重复序列作为整合载体同源重组位点可以通过提高外源基因在酿酒酵母基因组中拷贝数使外源基因在细胞中获得高效稳定表达.

In order to improve the copy number of heterologous genes in yeast genome, rDNA repeat units used as integration sites of homologous recombination has increased the concern of researchers. This paper introduced the structure and components of rDNA locus in Saccharomyces cerevisiae, and summarized the research progress of rDNA repetitive sequence as homologous recombination sites. A lot of research showed that hotl and some factors （Fob1, RAD52, MRX complexes, Sir2p, Sgsl and Mus81） regulated the copy number of rDNA unit, SmcS/Smc6 complexes and the sumoylation of RAD52 and Mms21 strictly regulated homologous recombination of rDNA and had important influence on the stability of rDNA. In addition, the stability of heterologous genes by rDNA mediated integration in mitotic phase had important relationship with the location and the characteristic of integration sites in rDNA unit and the size of the integrated vectors. Because homologous recombination occurred easily in Saccharomyces cerevisiae, the use of rDNA repetitive sequence as homologous recombination site could improve the copy number of heterologous genes in Saccharomyces cerevisiae, as the results heterologous genes would exist more stably and express efficiently in cells.