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

ZHOU Zhou,CAO Fang,CHEN Jiang-Ye^*
( State Key Laboratory of Molecular Biology,Institute of Biochemistry and Cell Biology,Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences,Shanghai 200031,China )

Abstract 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.
Key words Candida albicans; CaSRB9 gene; FLO8 gene; invasive growth; filamentous growth

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