CaSRB9基因的克隆及其在酿酒酵母形态发生中的作用

白色念珠菌是一种重要的人体致病真菌 ,致病机制与其形态发生紧密相关。酿酒酵母Flo8因子在其形态发生中起重要作用 ,我们把白色念珠菌基因组DNA导入酿酒酵母flo8基因缺失株中 ,筛选能够互补 flo8侵入生长缺陷的基因 ,分离到了一个与酿酒酵母SRB9同源的新基因 ,命名为CaSRB9。该基因全长 4998bp ,编码一种16 6 5个氨基酸的蛋白质。在双倍体酿酒酵母中CaSRB9可以部分互补MAPK途径基因缺失株以及 flo8缺失株的菌丝生长缺陷 ;在单倍体酿酒酵母中表达能够互补 flo8缺失株的侵入生长缺陷 ,但在MAPK途径基因缺失株中不能形成侵入生长

CaSRB9, a Novel Candida albicans Gene, Plays a Role in Morphogenesis of Saccharomyces cerevisiae

Candida albicans is the most frequently isolated fungal pathogen in humans. Many factors are involved in its morphological transition. Flo8 plays an important role in morphogenesis of Saccharomyces cerevisiae. In this work, a C.albicans genomic DNA library was introduced into an S.cerevisiae flo8/flo8 mutant to screen genes which could complement its invasive growth defect. In this screening, a novel gene was isolated and designated CaSRB9 (Candida albicans SRB9 gene). The CaSRB9 gene had an ORF of 4 998 bp, encoding a putative protein of 1 665 amino acids. The CaSrb9 shared highest similarity in amino acids (38%) with Srb9 of S.cerevisiae. Ectopic expression of the CaSRB9 gene in diploid S.cerevisiae suppressed defect in filamentous growth of some mutants in filamentation MAPK pathway (ste7/ste7, ste12/ste12, and tec1/tec1) and flo8/flo8 mutant under nitrogen starvation conditions. In haploid S.cerevisiae, ectopic expressed CaSrb9 complemented the invasive growth defect of flo8 mutant but failed to complement the invasive growth defects of the mutants in filamentation MAPK pathway.