Mattoon J R, Caravajal E, Guthrie D
Biotechnology Center, University of Colorado, Colorado Springs 80933-7150.
Curr Genet. 1990 Feb;17(2):179-83. doi: 10.1007/BF00312865.
Simultaneous effects of mutations in the transcriptional regulatory genes, HAP1, HAP2 and HAP3, on all respiratory cytochromes of Saccharomyces cerevisiae were determined. Cytochrome behavior in hap mutants and in cyc4 and rhm1 mutants, altered in regulation of 5-aminolevulinate synthase, was compared. Although hap mutants were isolated as trans-acting, transcriptional regulators of the CYC1 (iso-1-cytochrome c) gene, each mutant exhibits partial deficiencies in all cytochrome types. In hap2 and hap3 strains all cytochromes were decreased proportionally to about 40-50% of wild type values. In contrast, hap1 caused a decrease in all cytochromes and an accumulation of a pigment, probably Zn porphyrin. Apparently apocytochrome and heme biosynthesis retain coordination in hap2 and hap3, but not in hap1, mutants. Unlike cyc4 and rhm1 mutants, hap mutants do not exhibit 5-aminolevulinate-dependent restoration of cytochromes. The hap1 mutant grew at near-normal rates on glycerol, whereas hap2 and hap3 mutants grew very slowly. The frequency of [rho-] was high (16-18%) in hap2 and hap3 strains. Results are consistent with generalized control of mitochondrial replication directed by the HAP1-HAP2 system and heme-directed control of formation of all apocytochromes mediated by HAP1. Neither system exerts all-or-nothing control.
测定了转录调控基因HAP1、HAP2和HAP3中的突变对酿酒酵母所有呼吸细胞色素的同时影响。比较了hap突变体以及在5-氨基乙酰丙酸合酶调控方面发生改变的cyc4和rhm1突变体中的细胞色素行为。尽管hap突变体是作为CYC1（同工酶-1-细胞色素c）基因的反式作用转录调节因子分离得到的，但每个突变体在所有细胞色素类型中都表现出部分缺陷。在hap2和hap3菌株中，所有细胞色素均按比例减少至野生型值的约40-50%。相比之下，hap1导致所有细胞色素减少并积累一种色素，可能是锌卟啉。显然，脱辅基细胞色素和血红素生物合成在hap2和hap3突变体中保持协调，但在hap1突变体中则不然。与cyc4和rhm1突变体不同，hap突变体不表现出5-氨基乙酰丙酸依赖性的细胞色素恢复。hap1突变体在甘油上以接近正常的速率生长，而hap2和hap3突变体生长非常缓慢。hap2和hap3菌株中[rho-]的频率很高（16-18%）。结果与由HAP1-HAP2系统指导的线粒体复制的普遍控制以及由HAP1介导的所有脱辅基细胞色素形成的血红素指导控制一致。这两个系统都不施加全或无的控制。
