Bailey D A, Feldmann P J, Bovey M, Gow N A, Brown A J
Department of Molecular and Cell Biology, University of Aberdeen, United Kingdom.
J Bacteriol. 1996 Sep;178(18):5353-60. doi: 10.1128/jb.178.18.5353-5360.1996.
A hyphally regulated gene (HYR1) from the dimorphic human pathogenic fungus Candida albicans was isolated and characterized. Northern (RNA) analyses showed that the HYR1 mRNA was induced specifically in response to hyphal development when morphogenesis was stimulated by serum addition and temperature elevation, increases in both culture pH and temperature, or N-acetylglucosamine addition. The HYR1 gene sequence revealed a 937-codon open reading frame capable of encoding a protein with an N-terminal signal sequence, a C-terminal glycosylphosphatidylinositol-anchoring domain, 17 potential N glycosylation sites, and a large domain rich in serine and threonine (51% of 230 residues). These features are observed in many yeast cell wall proteins, but no homologs are present in the databases. In addition, Hyr1p contained a second domain rich in glycine, serine, and asparagine (79% of 239 residues). The HYR1 locus in C. albicans CAI4 was disrupted by "Ura-blasting," but the resulting homozygous delta hyr1/delta hyr1 null mutant displayed no obvious morphological phenotype. The growth rates for yeast cells and hyphae and the kinetics of germ tube formation in the null mutant were unaffected. Aberrant expression of HYR1 in yeast cells, when an ADH1-HYR1 fusion was used, did not stimulate hyphal formation in C. albicans or pseudohyphal growth in Saccharomyces cerevisiae. HYR1 appears to encode a nonessential component of the hyphal cell wall.
从二态性人类致病真菌白色念珠菌中分离并鉴定了一个菌丝调控基因（HYR1）。Northern（RNA）分析表明，当通过添加血清和升高温度、提高培养物pH值和温度或添加N-乙酰葡糖胺刺激形态发生时，HYR1 mRNA会特异性地响应菌丝发育而被诱导。HYR1基因序列显示有一个937个密码子的开放阅读框，能够编码一种具有N端信号序列、C端糖基磷脂酰肌醇锚定结构域、17个潜在N糖基化位点以及一个富含丝氨酸和苏氨酸的大结构域（230个残基中的51%）的蛋白质。这些特征在许多酵母细胞壁蛋白中都能观察到，但数据库中没有同源物。此外，Hyr1p含有另一个富含甘氨酸、丝氨酸和天冬酰胺的结构域（239个残基中的79%）。通过“URA敲除”破坏了白色念珠菌CAI4中的HYR1基因座，但产生的纯合缺失hyr1/hyr1突变体没有明显的形态学表型。该突变体中酵母细胞和菌丝的生长速率以及芽管形成的动力学均未受影响。当使用ADH1-HYR1融合体时，酵母细胞中HYR1的异常表达并未刺激白色念珠菌中的菌丝形成或酿酒酵母中的假菌丝生长。HYR1似乎编码菌丝细胞壁的一个非必需成分。
