Department of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610, United States.
Biochemistry. 2011 Mar 22;50(11):1901-9. doi: 10.1021/bi102000q. Epub 2011 Feb 4.
The assembly and stability of base excision repair (BER) proteins in vivo with abasic DNA and the role of adenomatous polyposis coli (APC) protein in this process are currently unclear. We have studied the assembly of a multiprotein BER complex onto abasic DNA (F-DNA) and characterized the physical and functional activity of the associated proteins. We found that the BER complex contained all the essential components of the long-patch BER system, such as APE1, Pol-β, Fen1, and DNA ligase I. Interestingly, wild-type APC was also present in the BER complex. Kinetics of the assembly of BER proteins onto the F-DNA were rapid and appeared in sequential order depending upon their requirement in the repair process. The presence of wild-type APC in the BER complex caused a decrease in the level of assembly of BER proteins and negatively affected long-patch BER. These results suggest that major BER proteins in the complex are assembled onto F-DNA and are competent in performing DNA repair. Wild-type APC in the BER complex reduces the repair activity, probably because of interaction with multiple components of the system.
体内碱基切除修复（BER）蛋白与无碱基 DNA 的组装以及腺瘤性息肉病（APC）蛋白在该过程中的作用目前尚不清楚。我们研究了多蛋白 BER 复合物在无碱基 DNA（F-DNA）上的组装，并对相关蛋白的物理和功能活性进行了表征。我们发现，BER 复合物包含长补丁 BER 系统的所有必需成分，如 APE1、Pol-β、Fen1 和 DNA 连接酶 I。有趣的是，野生型 APC 也存在于 BER 复合物中。BER 蛋白快速组装到 F-DNA 上，其组装顺序取决于它们在修复过程中的需求。野生型 APC 的存在降低了 BER 蛋白的组装水平，并对长补丁 BER 产生负面影响。这些结果表明，复合物中的主要 BER 蛋白组装到 F-DNA 上，并具有进行 DNA 修复的能力。BER 复合物中的野生型 APC 降低了修复活性，可能是由于与该系统的多个组件相互作用所致。
