The Saccharomyces cerevisiae PLB1 gene encodes a protein required for lysophospholipase and phospholipase B activity.
The Saccharomyces cerevisiae PLB1 gene encodes a protein required for lysophospholipase and phospholipase B activity.
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DOI：
10.1016/s0021-9258(17)32081-1
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发表时间：
1994-08
期刊：
影响因子：
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通讯作者：
K. S. Lee;J. Patton;M. Fido;L. K. Hines;S. Kohlwein;F. Paltauf;S. Henry;D. E. Levin
中科院分区：
文献类型：
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作者：
K. S. Lee;J. Patton;M. Fido;L. K. Hines;S. Kohlwein;F. Paltauf;S. Henry;D. E. Levin
从发芽酵母中分离到几种具有溶血磷脂酶/磷脂酶B活性的酶。在体外，这些酶能够分解所有可以从酵母细胞中提取的磷脂。已经从质膜中分离出两种形式的酶，从培养上清液和周质间隙中分离出第三种形式的酶，但它们的生物学作用尚未确定。据报道，这些高度糖基化的酶具有非常相似的催化性能，但在表观分子量方面有所不同。我们从酿酒酵母中分离到一个编码蛋白的基因，该蛋白的氨基酸序列与新青霉的磷脂酶B有45%的同源性。这个酵母基因，命名为PLB1，被定位在第八号染色体的左臂。通过对一个plb1 Delta突变体的提取液或培养上清液的检测，没有检测到溶血磷脂酶/磷脂酶B的残留活性。因此，要么PLB1基因编码先前检测到的所有磷脂酶B亚型，要么其基因产物是它们表达或激活所必需的。PLB1的缺失没有导致任何明显的表型缺陷，这表明我们未能确定会背叛这种缺陷的生长条件，或者Plb1p与另一种蛋白质在功能上是多余的，其活性尚未被检测到。一个plb1 Delta突变体将野生型水平的可溶性磷脂酰肌醇代谢产物甘油磷脂释放到生长介质中，但大大降低了相应磷脂酰胆碱和磷脂酰乙醇胺代谢物的水平。这些结果表明，磷脂酰胆碱和磷脂酰乙醇胺的脱酰基产物主要是PLB1，而不是磷脂酰肌醇。
Several enzymes with lysophospholipase/phospholipase B activity have been described from the budding yeast Saccharomyces cerevisiae. In vitro, these enzymes are capable of hydrolyzing all phospholipids that can be extracted from yeast cells. Two forms of the enzyme have been isolated from plasma membranes and a third from culture supernatants and the periplasmic space, but their biological roles have not been determined. These highly glycosylated enzymes were reported to have very similar catalytic properties but differed with respect to apparent molecular weight. We isolated a gene from S. cerevisiae, encoding a protein predicted to share 45% amino acid sequence identity with phospholipase B from Penicillium notatum. This yeast gene, designated PLB1, was mapped to the left arm of chromosome VIII. No residual lysophospholipase/phospholipase B activity was detected upon assay of extracts or culture supernatants of a plb1 delta mutant. Thus, either the PLB1 gene encodes all of the previously detected isoforms of phospholipase B or its gene product is required for their expression or activation. Deletion of PLB1 did not result in any apparent phenotypic defect, suggesting either that we failed to identify the growth conditions that would betray such a defect or that Plb1p is functionally redundant with another protein, whose activity has gone undetected. A plb1 delta mutant released wild-type levels of the soluble phosphatidylinositol metabolite glycerophosphoinositol into the growth medium but released greatly reduced levels of the corresponding phosphatidylcholine and phosphatidylethanolamine metabolites. These results indicate that PLB1 is principally responsible for the production of the deacylation products of phosphatidylcholine and phosphatidylethanolamine but not phosphatidylinositol.