Hernando Y, Carter A T, Parr A, Hove-Jensen B, Schweizer M
Genetics and Microbiology Department, Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, United Kingdom.
J Biol Chem. 1999 Apr 30;274(18):12480-7. doi: 10.1074/jbc.274.18.12480.
The PRS gene family in Saccharomyces cerevisiae consists of five genes each capable of encoding a 5-phosphoribosyl-1(alpha)-pyrophosphate synthetase polypeptide. To gain insight into the functional organization of this gene family we have constructed a collection of strains containing all possible combinations of disruptions in the five PRS genes. Phenotypically these deletant strains can be classified into three groups: (i) a lethal phenotype that corresponds to strains containing a double disruption in PRS2 and PRS4 in combination with a disruption in either PRS1 or PRS3; simultaneous deletion of PRS1 and PRS5 or PRS3 and PRS5 are also lethal combinations; (ii) a second phenotype that is encountered in strains containing disruptions in PRS1 and PRS3 together or in combination with any of the other PRS genes manifests itself as a reduction in growth rate, enzyme activity, and nucleotide content; (iii) a third phenotype that corresponds to strains that, although affected in their phosphoribosyl pyrophosphate-synthesizing ability, are unimpaired for growth and have nucleotide profiles virtually the same as the wild type. Deletions of PRS2, PRS4, and PRS5 or combinations thereof cause this phenotype. These results suggest that the polypeptides encoded by the members of the PRS gene family may be organized into two functional entities. Evidence that these polypeptides interact with each other in vivo was obtained using the yeast two-hybrid system. Specifically PRS1 and PRS3 polypeptides interact strongly with each other, and there are significant interactions between the PRS5 polypeptide and either the PRS2 or PRS4 polypeptides. These data suggest that yeast phosphoribosyl pyrophosphate synthetase exists in vivo as multimeric complex(es).
酿酒酵母中的PRS基因家族由五个基因组成，每个基因都能够编码一种5-磷酸核糖-1（α）-焦磷酸合成酶多肽。为了深入了解这个基因家族的功能组织，我们构建了一系列菌株，其中包含五个PRS基因中所有可能的破坏组合。从表型上看，这些缺失菌株可分为三组：（i）致死表型，对应于在PRS2和PRS4中存在双重破坏并与PRS1或PRS3中的一个破坏相结合的菌株；同时缺失PRS1和PRS5或PRS3和PRS5也是致死组合；（ii）第二种表型，出现在同时含有PRS1和PRS3破坏或与任何其他PRS基因组合破坏的菌株中，表现为生长速率、酶活性和核苷酸含量降低；（iii）第三种表型，对应于那些虽然其磷酸核糖焦磷酸合成能力受到影响，但生长不受损害且核苷酸谱与野生型几乎相同的菌株。缺失PRS2、PRS4和PRS5或它们的组合会导致这种表型。这些结果表明，PRS基因家族成员编码的多肽可能被组织成两个功能实体。使用酵母双杂交系统获得了这些多肽在体内相互作用的证据。具体而言，PRS1和PRS3多肽彼此强烈相互作用，并且PRS5多肽与PRS2或PRS4多肽之间存在显著相互作用。这些数据表明酵母磷酸核糖焦磷酸合成酶在体内以多聚体复合物的形式存在。
