Reichert U, Winter M
J Bacteriol. 1975 Dec;124(3):1041-5. doi: 10.1128/jb.124.3.1041-1045.1975.
Triploid and tetraploid Saccharomyces strains containing different combinations of a gua-1 mutant allele and the corresponding wild type were prepared. The cultivation of the different strains in media upon which the mutant fails to grow leads to a pronounced growth rate response to the dosage of the wild-type allele. Proportionality between the specific activity of the guanosine 5'-monophosphate synthetase and the wild-type dosage was reavealed. Inosine 5'-monophosphate dehydrogenase, the precursor enzyme in the pathway, is derepressed in a sigmoid manner when the wild-type dosage is reduced, whereas the activity of cytosine deaminase, investigated as a reference enzyme, is less affected.
制备了含有gua-1突变等位基因和相应野生型不同组合的三倍体和四倍体酿酒酵母菌株。在突变体无法生长的培养基上培养不同菌株，会导致对野生型等位基因剂量产生明显的生长速率反应。揭示了鸟苷5'-单磷酸合成酶的比活性与野生型剂量之间的比例关系。该途径中的前体酶肌苷5'-单磷酸脱氢酶，在野生型剂量降低时以S形方式去阻遏，而作为参照酶研究的胞嘧啶脱氨酶的活性受影响较小。
