Characterization of null mutants of the RAD55 gene of Saccharomyces cerevisiae: effects of temperature, osmotic strength and mating type.
Characterization of null mutants of the RAD55 gene of Saccharomyces cerevisiae: effects of temperature, osmotic strength and mating type.
复制标题
酿酒酵母 RAD55 基因无效突变体的表征：温度、渗透强度和交配类型的影响。
DOI：
10.1093/genetics/116.4.547
复制
发表时间：
1987
期刊：
影响因子：
3.3
通讯作者：
Mortimer,RK
中科院分区：
文献类型：
--
作者：
Lovett,ST;Mortimer,RK
RAD 55属于一组抵抗电离辐射所需的基因，RAD 50-RAD 57，它们被认为定义了重组修复途径。由于RAD 55的所有四个等位基因对于它们的辐射表型都是温度条件性的（冷敏感的），我们研究了由RAD 55基因中的无效突变产生的表型，在体外构建并易位到酵母染色体上。这些无效突变株的X-射线敏感性令人惊讶地被抑制的温度升高，渗透强度的生长介质和杂合性在交配型位点。这前两个属性，温度条件性和渗透补救性，通常与错义突变; thesrad 55 null突变体是独特的，因为它们表现出这些属性，虽然突变基因不能表达。射线诱导的有丝分裂重组也是冷敏感的inrad 55突变体二倍体。虽然有丝分裂生长不受影响，在这些菌株，减数分裂是一个致命的事件在高温和低温。尽管frad 55无效突变体的表型与RAD 55在重组和重组修复中的作用一致，但有证据表明，至少在有丝分裂细胞中，存在可解释的RAD 55非依赖性重组，其受温度和MAT的影响。我们讨论了RAD 55在重组中的作用模型，以解释RAD 55突变体的不寻常特性。
RAD55belongs to a group of genes required for resistance to ionizing radiation,RAD50-RAD57, which are thought to define a pathway of recombinational repair. Since all four alleles ofRAD55are temperature conditional (cold sensitive) for their radiation phenotype, we investigated the phenotype produced by null mutations in theRAD55gene, constructedin vitroand transplaced to the yeast chromosome. The X-ray sensitivity of these null mutant strains was surprisingly suppressed by increased temperature, osmotic strength of the growth medium and heterozygosity at the mating-type locus. These first two properties, temperature conditionality and osmotic remediability, are commonly associated with missense mutations; theserad55null mutants are unique in that they exhibit these properties although the mutant gene cannot be expressed. X-ray-induced mitotic recombination was also cold sensitive inrad55mutant diploids. Although mitotic growth was unaffected in these strains, meiosis was a lethal event at both high and low temperatures. Whereas the phenotype ofrad55null mutants is consistent with a role ofRAD55in recombination and recombinational repair, there is evidence for considerableRAD55-independent recombination, at least in mitotic cells, which is influenced by temperature andMAT. We discuss models for the role ofRAD55in recombination to explain the unusual properties ofrad55mutants.