Requirement for three novel protein complexes in the absence of the Sgs1 DNA helicase in Saccharomyces cerevisiae.
Requirement for three novel protein complexes in the absence of the Sgs1 DNA helicase in Saccharomyces cerevisiae.
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发表时间：
2001
期刊：
影响因子：
3.3
通讯作者：
J. Mullen;Vivek Kaliraman;Samer S. Ibrahim;S. Brill
中科院分区：
文献类型：
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作者：
J. Mullen;Vivek Kaliraman;Samer S. Ibrahim;S. Brill
酿酒酵母Sgs 1蛋白是RecQ DNA解旋酶家族的成员，是基因组稳定性所需，但不是细胞活力所需。为了鉴定在Sgs 1不存在的情况下起作用的蛋白质，进行了合成致死筛选。我们在六个互补组中获得了突变，我们称之为SLX基因。大多数SLX基因编码在其他物种中保守的未表征的开放阅读框。这些基因中没有一个是生存所必需的，并且所有SLX无效突变都是合成致死的，其中TOP3中的突变编码SGS 1相互作用的DNA拓扑异构酶。无效突变体的分析确定了一对基因在三个表型类的每一个。MMS 4（SLX 2）和SLX 3中的突变产生相同的表型，包括弱UV和强MMS超敏性，孢子形成完全丧失，以及TOP1突变的合成生长缺陷。Mms 4和Slx 3蛋白从细胞提取物中共免疫沉淀，表明它们在复合物中起作用。SLX 5和SLX 8的突变产生了对羟基脲的敏感性，孢子形成效率降低，以及以异质菌落形态为特征的缓慢生长表型。Slx 5和Slx 8蛋白含有RING指结构域，并从细胞提取物中共免疫沉淀。SLX 1和SLX 4基因是在限制性温度下sgs 1温度敏感等位基因存在下生存所需的，并且Slx 1和Slx 4蛋白在细胞提取物中类似地相关。我们建议，MMS 4/SLX 3，SLX 5/8和SLX 1/4基因对编码异二聚体复合物，并推测这些复合物是需要解决的重组中间体，出现在响应DNA损伤，在减数分裂过程中，在没有SGS 1/TOP 3。
The Saccharomyces cerevisiae Sgs1 protein is a member of the RecQ family of DNA helicases and is required for genome stability, but not cell viability. To identify proteins that function in the absence of Sgs1, a synthetic-lethal screen was performed. We obtained mutations in six complementation groups that we refer to as SLX genes. Most of the SLX genes encode uncharacterized open reading frames that are conserved in other species. None of these genes is required for viability and all SLX null mutations are synthetically lethal with mutations in TOP3, encoding the SGS1-interacting DNA topoisomerase. Analysis of the null mutants identified a pair of genes in each of three phenotypic classes. Mutations in MMS4 (SLX2) and SLX3 generate identical phenotypes, including weak UV and strong MMS hypersensitivity, complete loss of sporulation, and synthetic growth defects with mutations in TOP1. Mms4 and Slx3 proteins coimmunoprecipitate from cell extracts, suggesting that they function in a complex. Mutations in SLX5 and SLX8 generate hydroxyurea sensitivity, reduced sporulation efficiency, and a slow-growth phenotype characterized by heterogeneous colony morphology. The Slx5 and Slx8 proteins contain RING finger domains and coimmunoprecipitate from cell extracts. The SLX1 and SLX4 genes are required for viability in the presence of an sgs1 temperature-sensitive allele at the restrictive temperature and Slx1 and Slx4 proteins are similarly associated in cell extracts. We propose that the MMS4/SLX3, SLX5/8, and SLX1/4 gene pairs encode heterodimeric complexes and speculate that these complexes are required to resolve recombination intermediates that arise in response to DNA damage, during meiosis, and in the absence of SGS1/TOP3.