Table_2_Genes and Proteomes Associated With Increased Mutation Frequency and Multidrug Resistance of Naturally Occurring Mismatch Repair-Deficient Salmonella Hypermutators.DOCX

The emergence of antibiotic-resistant Salmonella through mutations led to mismatch repair (MMR) deficiency that represents a potential hazard to public health. Here, four representative MMR-deficient Salmonella hypermutator strains and Salmonella Typhimurium LT2 were used to comprehensively reveal the influence of MMR deficiency on antibiotic resistance among Salmonella. Our results indicated that the mutation frequency ranged from 3.39 × 10–4 to 5.46 × 10–2 in the hypermutator. Mutation sites in MutS, MutL, MutT, and UvrD of the four hypermutators were all located in the essential and core functional regions. Mutation frequency of the hypermutator was most highly correlated with the extent of mutation in MutS. Mutations in MMR genes (mutS, mutT, mutL, and uvrD) were correlated with increased mutation in antibiotic resistance genes, and the extent of antibiotic resistance was significantly correlated with the number of mutation sites in MutL and in ParC. The number of mutation sites in MMR genes and antibiotic resistance genes exhibited a significant positive correlation with the number of antibiotics resisted and with expression levels of mutS, mutT, and mutL. Compared to Salmonella Typhimurium LT2, a total of 137 differentially expressed and 110 specifically expressed proteins were identified in the four hypermutators. Functional enrichment analysis indicated that the proteins significantly overexpressed in the hypermutators primarily associated with translation and stress response. Interaction network analysis revealed that the ribosome pathway might be a critical factor for high mutation frequency and multidrug resistance in MMR-deficient Salmonella hypermutators. These results help elucidate the mutational dynamics that lead to hypermutation, antibiotic resistance, and activation of stress response pathways in Salmonella.

抗菌素耐药性沙门氏菌通过突变而产生的不匹配修复（MMR）缺陷，构成了对公共健康的潜在威胁。本研究中，我们选取了四种具有代表性的MMR缺陷型沙门氏菌高突变株以及沙门氏菌鼠伤寒LT2菌株，全面揭示了MMR缺陷对沙门氏菌中抗菌素耐药性的影响。研究结果显示，高突变株的突变频率介于3.39 × 10–4至5.46 × 10–2之间。在四种高突变株中，MutS、MutL、MutT和UvrD的突变位点均位于关键的核心功能区域。高突变株的突变频率与MutS中的突变程度高度相关。MMR基因（mutS、mutT、mutL和uvrD）的突变与抗菌素耐药基因的突变增加相关，抗菌素耐药性的程度与MutL和ParC中的突变位点数量显著相关。MMR基因和抗菌素耐药基因的突变位点数量与所抵抗的抗菌素数量以及mutS、mutT和mutL的表达水平呈显著正相关。与沙门氏菌鼠伤寒LT2相比，在四种高突变株中鉴定出137种差异表达和110种特异性表达的蛋白质。功能富集分析表明，在高突变株中显著过表达的蛋白质主要与翻译和应激反应相关。相互作用网络分析揭示了核糖体途径可能是MMR缺陷型沙门氏菌高突变株中高突变频率和多药耐药的关键因素。这些研究结果有助于阐明导致沙门氏菌中高突变、抗菌素耐药以及应激反应途径激活的突变动力学。