Grazielle-Silva Viviane, Zeb Tehseen Fatima, Burchmore Richard, Machado Carlos Renato, McCulloch Richard, Teixeira Santuza M R
Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
The Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom.
Front Cell Infect Microbiol. 2020 Apr 16;10:154. doi: 10.3389/fcimb.2020.00154. eCollection 2020.
MSH2, associated with MSH3 or MSH6, is a central component of the eukaryotic DNA Mismatch Repair (MMR) pathway responsible for the recognition and correction of base mismatches that occur during DNA replication and recombination. Previous studies have shown that MSH2 plays an additional DNA repair role in response to oxidative damage in and . By performing co-immunoprecipitation followed by mass spectrometry with parasites expressing tagged proteins, we confirmed that the parasites' MSH2 forms complexes with MSH3 and MSH6. To investigate the involvement of these two other MMR components in the oxidative stress response, we generated knockout mutants of MSH6 and MSH3 in bloodstream forms and MSH6 mutants in epimastigotes. Differently from the phenotype observed with MSH2 knockout epimastigotes, loss of one or two alleles of resulted in increased susceptibility to H exposure, besides impaired MMR. In contrast, or null mutants displayed increased tolerance to MNNG treatment, indicating that MMR is affected, but no difference in the response to H treatment when compared to wild type cells. Taken together, our results suggest that, while MSH6 and MSH2 are involved with the oxidative stress response in addition to their role as components of the MMR, the DNA repair pathway that deals with oxidative stress damage operates differently in .
与MSH3或MSH6相关联的MSH2是真核生物DNA错配修复（MMR）途径的核心组成部分，负责识别和纠正DNA复制和重组过程中出现的碱基错配。先前的研究表明，MSH2在应对[具体生物1]和[具体生物2]中的氧化损伤时还发挥额外的DNA修复作用。通过对表达标签蛋白的寄生虫进行免疫共沉淀后再进行质谱分析，我们证实了寄生虫的MSH2与MSH3和MSH6形成复合物。为了研究这两个其他MMR组分在氧化应激反应中的作用，我们构建了[具体生物1]血流形式的MSH6和MSH3基因敲除突变体以及[具体生物2]前鞭毛体的MSH6突变体。与MSH2基因敲除前鞭毛体所观察到的表型不同，[具体生物1]或[具体生物2]一个或两个等位基因的缺失除了导致MMR受损外，还增加了对H暴露的敏感性。相反，[具体生物1]或[具体生物2]的基因敲除突变体对MNNG处理表现出更高的耐受性，这表明MMR受到影响，但与野生型细胞相比，在对H处理的反应上没有差异。综上所述，我们的结果表明，虽然MSH6和MSH2除了作为MMR的组分发挥作用外，还参与氧化应激反应，但在[具体生物1]和[具体生物2]中处理氧化应激损伤的DNA修复途径运作方式不同。
