Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306.
The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210.
Proc Natl Acad Sci U S A. 2022 Mar 8;119(10):e2118940119. doi: 10.1073/pnas.2118940119. Epub 2022 Mar 1.
SignificanceBase excision repair (BER) is one of the major DNA repair pathways used to fix a myriad of cellular DNA lesions. The enzymes involved in BER, including DNA polymerase β (Polβ), have been identified and characterized, but how they act together to efficiently perform BER has not been fully understood. Through gel electrophoresis, mass spectrometry, and kinetic analysis, we discovered that the two enzymatic activities of Polβ can be interlocked, rather than functioning independently from each other, when processing DNA intermediates formed in BER. The finding prompted us to hypothesize a modified BER pathway. Through conventional and time-resolved X-ray crystallography, we solved 11 high-resolution crystal structures of cross-linked Polβ complexes and proposed a detailed chemical mechanism for Polβ's 5'-deoxyribose-5-phosphate lyase activity.
碱基切除修复（BER）是一种主要的 DNA 修复途径，用于修复细胞内多种 DNA 损伤。参与 BER 的酶，包括 DNA 聚合酶 β（Polβ），已经被鉴定和表征，但它们如何共同有效地进行 BER 还没有被完全理解。通过凝胶电泳、质谱和动力学分析，我们发现 Polβ 的两种酶活性在处理 BER 中形成的 DNA 中间体时可以相互锁定，而不是彼此独立地发挥作用。这一发现促使我们提出了一种改良的 BER 途径。通过传统和时间分辨的 X 射线晶体学，我们解决了 11 个交联 Polβ 复合物的高分辨率晶体结构，并提出了 Polβ 的 5'-脱氧核糖-5-磷酸裂解酶活性的详细化学机制。
