Liljelund P, Losson R, Kammerer B, Lacroute F
J Mol Biol. 1984 Dec 5;180(2):251-65. doi: 10.1016/s0022-2836(84)80003-0.
The Saccharomyces cerevisiae gene PPR1 encodes a positive regulator of the expression of the two unlinked structural genes URA1 and URA3. The gene has been mapped to a position 6.5 cM from the centromere of chromosome XII. Uninducible alleles have been selected and used to establish a meiotic map. Suppressible alleles have been identified. The sequencing of a suppressible allele confirms the nonsense nature of the mutation as well as the reading frame deduced from the nucleotide sequence. No evidence of intracistronic complementation was found, and enzymatic analysis of leaky mutants did not reveal any mutations dissociating regulation of URA1 from that of URA3. Three in vitro-constructed deletions of PPR1 have been integrated at the chromosomal locus, giving strains with a completely negative phenotype. These deletion mutants display the wild-type basal level of URA1 and URA3 expression and show a semi-dominant phenotype in heteroallelic ppr1+/ppr1-delta diploids. Amplifying PPR1 by introduction into yeast on a multicopy vector increases the induction factor of URA1 and URA3 expression. These results show that the extent of regulation of the two structural genes is dependent on the concentration of the active PPR1 protein.
酿酒酵母基因PPR1编码两个不连锁的结构基因URA1和URA3表达的正调控因子。该基因已被定位到离第十二号染色体着丝粒6.5厘摩的位置。已筛选出不可诱导的等位基因并用于构建减数分裂图谱。已鉴定出可抑制的等位基因。对一个可抑制等位基因的测序证实了突变的无义性质以及从核苷酸序列推导的阅读框。未发现顺反子内互补的证据，对渗漏突变体的酶学分析也未揭示任何使URA1的调控与URA3的调控分离的突变。三个体外构建的PPR1缺失已整合到染色体位点，产生具有完全阴性表型的菌株。这些缺失突变体显示出URA1和URA3表达的野生型基础水平，并在杂合等位基因ppr1+/ppr1-δ二倍体中表现出半显性表型。通过在多拷贝载体上导入酵母来扩增PPR1会增加URA1和URA3表达的诱导因子。这些结果表明，两个结构基因的调控程度取决于活性PPR1蛋白的浓度。
