Grabowska Ewa, Wronska Urszula, Denkiewicz Milena, Jaszczur Malgorzata, Respondek Aleksandra, Alabrudzinska Malgorzata, Suski Catherine, Makiela-Dzbenska Karolina, Jonczyk Piotr, Fijalkowska Iwona J
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106, Warsaw, Poland.
Mol Microbiol. 2014 May;92(4):659-80. doi: 10.1111/mmi.12580. Epub 2014 Apr 15.
The role of replicative DNA polymerases in ensuring genome stability is intensively studied, but the role of other components of the replisome is still not fully understood. One of such component is the GINS complex (comprising the Psf1, Psf2, Psf3 and Sld5 subunits), which participates in both initiation and elongation of DNA replication. Until now, the understanding of the physiological role of GINS mostly originated from biochemical studies. In this article, we present genetic evidence for an essential role of GINS in the maintenance of replication fidelity in Saccharomyces cerevisiae. In our studies we employed the psf1-1 allele (Takayama et al., 2003) and a novel psf1-100 allele isolated in our laboratory. Analysis of the levels and specificity of mutations in the psf1 strains indicates that the destabilization of the GINS complex or its impaired interaction with DNA polymerase epsilon increases the level of spontaneous mutagenesis and the participation of the error-prone DNA polymerase zeta. Additionally, a synergistic mutator effect was found for the defects in Psf1p and in the proofreading activity of Pol epsilon, suggesting that proper functioning of GINS is crucial for facilitating error-free processing of terminal mismatches created by Pol epsilon.
复制性DNA聚合酶在确保基因组稳定性中的作用已得到深入研究，但复制体其他组分的作用仍未完全明确。其中一个组分是GINS复合物（由Psf1、Psf2、Psf3和Sld5亚基组成），它参与DNA复制的起始和延伸过程。到目前为止，对GINS生理作用的理解大多源于生化研究。在本文中，我们提供了遗传学证据，证明GINS在酿酒酵母复制保真度维持中起关键作用。在我们的研究中，我们使用了psf1-1等位基因（Takayama等人，2003年）以及我们实验室分离出的一个新的psf1-100等位基因。对psf1菌株中突变水平和特异性的分析表明，GINS复合物的不稳定或其与DNA聚合酶ε相互作用受损会增加自发诱变水平以及易出错的DNA聚合酶ζ的参与度。此外，还发现Psf1p缺陷与Pol ε校对活性缺陷之间存在协同诱变效应，这表明GINS的正常功能对于促进Pol ε产生的末端错配的无错处理至关重要。
