Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC, UNC-CONICET), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA Córdoba, Argentina and Centro de Excelencia en Productos, Procesos e Innovación Tecnológica de la Provincia de Córdoba (CEPROCOR), Pabellón CEPROCOR (X5164), Santa María de Punilla, Córdoba, Argentina.
J Biochem. 2013 Dec;154(6):505-11. doi: 10.1093/jb/mvt080. Epub 2013 Aug 21.
The hallmark of the mismatch repair system in bacterial and eukaryotic organisms devoid of MutH is the presence of a MutL homologue with endonuclease activity. The aim of this study was to analyse whether different DNA structures affect Pseudomonas aeruginosa MutL (PaMutL) endonuclease activity and to determine if a specific nucleotide sequence is required for this activity. Our results showed that PaMutL was able to nick covalently closed circular plasmids but not linear DNA at high ionic strengths, while the activity on linear DNA was only found below 60 mM salt. In addition, single strand DNA, ss/ds DNA boundaries and negatively supercoiling degree were not required for PaMutL nicking activity. Finally, the analysis of the incision sites revealed that PaMutL, as well as Bacillus thuringiensis MutL homologue, did not show DNA sequence specificity.
细菌和真核生物中缺乏 MutH 的错配修复系统的标志是存在具有内切核酸酶活性的 MutL 同源物。本研究旨在分析不同的 DNA 结构是否会影响铜绿假单胞菌 MutL（PaMutL）内切核酸酶活性，并确定是否需要特定的核苷酸序列来实现这种活性。我们的结果表明，PaMutL 能够在高离子强度下切割共价闭合环状质粒，但不能切割线性 DNA，而在线性 DNA 上的活性仅在低于 60mM 盐的情况下才被发现。此外，单链 DNA、ss/ds DNA 边界和负超螺旋程度都不是 PaMutL 切口活性所必需的。最后，对切口部位的分析表明，PaMutL 与苏云金芽孢杆菌 MutL 同源物一样，没有显示 DNA 序列特异性。
