White T C, Agabian N
Intercampus Program in Molecular Parasitology, University of California at San Francisco 94118, USA.
J Bacteriol. 1995 Sep;177(18):5215-21. doi: 10.1128/jb.177.18.5215-5221.1995.
For the pathogenic yeast Candida albicans, secreted aspartyl proteinase (Sap) activity has been correlated with virulence. A family consisting of at least eight SAP genes can be drawn upon to produce Sap enzymatic activity. In this study, the levels of Sap1, Sap2, and Sap3 isoenzymes were monitored under a variety of growth conditions for several strains, including strain WO-1, which alternates between two switch phenotypes, white (W) and opaque (O). When cultured under proteinase-inducing conditions, most strains and W cells produce Sap2, while O cells produce Sap1, Sap2, and Sap3. Both W and O cells of strain WO-1 produce Saps in enriched and defined media that do not induce Saps from other strains. The specific Sap isoenzyme that is produced is determined by the cell type, while the level of Sap production is determined by environmental factors. The levels and temporal regulation of the SAP mRNAs as determined by Northern (RNA) analysis were consistent with Sap protein levels and with previous results. S1 analysis showed that SAP6 is the predominant SAP gene transcribed during hyphal induction at neutral pH. These studies define the culture conditions which control the levels of SAP mRNAs and Sap proteins, and they indicate that both the yeast/hyphal transition and phenotypic switching can determine which of the Sap isoenzymes is produced.
对于致病性酵母白色念珠菌，分泌天冬氨酸蛋白酶（Sap）活性与毒力相关。一个由至少八个SAP基因组成的家族可用于产生Sap酶活性。在本研究中，监测了几种菌株（包括在白色（W）和不透明（O）两种转换表型之间交替的WO-1菌株）在各种生长条件下Sap1、Sap2和Sap3同工酶的水平。在蛋白酶诱导条件下培养时，大多数菌株和W细胞产生Sap2，而O细胞产生Sap1、Sap2和Sap3。WO-1菌株的W细胞和O细胞在富集培养基和限定培养基中均产生Saps，而这些培养基不会诱导其他菌株产生Saps。产生的特定Sap同工酶由细胞类型决定，而Sap产生的水平由环境因素决定。通过Northern（RNA）分析确定的SAP mRNA的水平和时间调控与Sap蛋白水平以及先前的结果一致。S1分析表明，SAP6是在中性pH下菌丝诱导过程中转录的主要SAP基因。这些研究确定了控制SAP mRNA和Sap蛋白水平的培养条件，并且表明酵母/菌丝转变和表型转换均可决定产生哪种Sap同工酶。
