Mutants of yeast defective in sucrose utilization.
Mutants of yeast defective in sucrose utilization.
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发表时间：
1981-05
期刊：
影响因子：
3.3
通讯作者：
M. Carlson;B. Osmond;D. Botstein
中科院分区：
文献类型：
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作者：
M. Carlson;B. Osmond;D. Botstein
在酵母中，蔗糖作为碳源和能源的利用是由经典的SUC基因控制的，这些基因赋予了产生蔗糖降解酶转移酶的能力(Mortimer和Hawthorne 1969)。对不能在蔗糖上厌氧生长但仍能利用葡萄糖的酿酒酵母菌株S288C(SUC2+)进行了分离。确定了两个主要的互补组：24个位于SUC2基因座的隐性突变(SUC2-)和5个隐性突变，定义了一个新的基因座SNF1(用于蔗糖非发酵)，这是蔗糖利用所必需的。还鉴定了两个次要的互补组，每个组由一个具有泄漏的蔗糖非发酵表型的成员组成。分离到的SUC2突变包括4个可抑制的琥珀突变和5个明显表现出基因内互补的突变；互补分析和有丝分裂图谱研究表明，所有的SUC2突变都是单个基因的等位基因。这些结果表明，SUC2编码一种蛋白质，可能是二聚体或多聚体。在SUC2中未检测到转化酶活性，可能是二聚体或多聚体。在SUC2突变体中没有检测到转化酶活性，SNF1基因座与SUC2没有紧密连锁。SNF1突变被发现是多效性的，阻止了SUC2+和SUC7+菌株对蔗糖的利用，也阻止了半乳糖、麦芽糖和几种非发酵碳源的利用。虽然SNF1突变体因此表现出矮小的表型，但经典的矮小突变并不干扰蔗糖、半乳糖或麦芽糖的利用。受SNF1影响的所有碳利用系统的一个共同特征是，所有系统都受到葡萄糖抑制的调节。SNF1突变体被发现能产生构成非糖基化形式的转化酶，但不能产生葡萄糖抑制的、糖基化的分泌型转化酶。这种失败不能归因于糖化和分泌蛋白生产的普遍缺陷，因为酸性磷酸酶的合成没有受到SNF1突变的影响。酸性磷酸酶是一种不受葡萄糖抑制的糖基化分泌蛋白。这些发现表明，SNF1基因座参与了葡萄糖抑制对基因表达的调节。
Utilization of sucrose as a source of carbon and energy in yeast (Saccharomyces) is controlled by the classical SUC genes, which confer the ability to produce the sucrose-degrading enzyme invertase (Mortimer and Hawthorne 1969). Mutants of S. cerevisiae strain S288C (SUC2+) unable to grow anaerobically on sucrose, but still able to use glucose, were isolated. Two major complementation groups were identified: twenty-four recessive mutations at the SUC2 locus (suc2-); and five recessive mutations defining a new locus, SNF1 (for sucrose nonfermenting), essential for sucrose utilization. Two minor complementation groups, each comprising a single member with a leaky sucrose-nonfermenting phenotype, were also identified. The Suc2 mutations isolated include four suppressible amber mutations and five mutations apparently exhibiting intragenic complementation; complementation analysis and mitotic mapping studies indicated that all of the suc2 mutations are alleles of a single gene. These results suggest that SUC2 encodes a protein, probably a dimer or multimer. No invertase activity was detected in suc2 probably a dimer or multimer. No invertase activity was detected in suc2 mutants,--The SNF1 locus is not tightly linked to SUC2. The snf1 mutations were found to be pleiotropic, preventing sucrose utilization by SUC2+ and SUC7+ strains, and also preventing utilization of galactose, maltose and several nonfermentable carbon sources. Although snf1 mutants thus display a petite phenotype, classic petite mutations do not interfere with utilization of sucrose, galactose or maltose. A common feature of all the carbon utilization systems affected by SNF1 is that all are regulated by glucose repression. The snf1 mutants were found to produce the constitutive nonglycosylated form of invertase, but failed to produce the glucose-repressible, glycosylated, secreted invertase. This failure cannot be attributed to a general defect in production of glycosylated and secreted proteins because synthesis of acid phosphatase, a glycosylated secreted protein not subject to glucose repression, was not affected by snf1 mutations. These findings suggest that the SNF1 locus is involved in the regulation of gene expression by glucose repression.