McMahon L W, Sangerman J, Goodman S R, Kumaresan K, Lambert M W
Department of Pathology and Laboratory Medicine and Graduate School of Biomedical Sciences, UMDNJ-New Jersey Medical School, Newark, New Jersey 07103, USA.
Biochemistry. 2001 Jun 19;40(24):7025-34. doi: 10.1021/bi002917g.
Repair of DNA interstrand cross-links is a complex process critical to which is the identification of sites of damage by specific proteins. We have recently identified the structural protein nonerythroid alpha spectrin (alphaSpIISigma) as a component of a nuclear protein complex in normal human cells which is involved in the repair of DNA interstrand cross-links and have shown that it forms a complex with the Fanconi anemia proteins FANCA, FANCC, and FANCG. Using DNA affinity chromatography, we now show that alphaSpIISigma, present in HeLa cell nuclei, specifically binds to DNA containing psoralen interstrand cross-links and that the FANCA, FANCC, and FANCG proteins are bound to this damaged DNA as well. That spectrin binds directly to the cross-linked DNA has been shown using purified bovine brain spectrin (alphaSpIISigma1/betaSpIISigma1)2. Binding of the Fanconi anemia (FA) proteins to the damaged DNA may be either direct or indirect via their association with alphaSpIISigma. These results demonstrate a role for alpha spectrin in the nucleus as well as a new function for this protein in the cell, an involvement in DNA repair. alphaSpIISigma may bind to cross-linked DNA and act as a scaffold to help in the recruitment of repair proteins to the site of damage and aid in their alignment and interaction with each other, thus enhancing the efficiency of the repair process.
DNA链间交联的修复是一个复杂的过程，其中关键的是特定蛋白质对损伤位点的识别。我们最近鉴定出结构蛋白非红细胞α-血影蛋白（αSpIISigma）是正常人类细胞中核蛋白复合物的一个组成部分，该复合物参与DNA链间交联的修复，并且已表明它与范可尼贫血蛋白FANCA、FANCC和FANCG形成复合物。利用DNA亲和层析，我们现在表明存在于HeLa细胞核中的αSpIISigma特异性结合含有补骨脂素链间交联的DNA，并且FANCA、FANCC和FANCG蛋白也结合到这种受损DNA上。使用纯化的牛脑血影蛋白（αSpIISigma1/βSpIISigma1）2已表明血影蛋白直接结合交联的DNA。范可尼贫血（FA）蛋白与受损DNA的结合可能是直接的，也可能是通过它们与αSpIISigma的关联间接实现的。这些结果证明了α-血影蛋白在细胞核中的作用以及该蛋白在细胞中的一项新功能，即参与DNA修复。αSpIISigma可能结合交联的DNA并作为一个支架，帮助将修复蛋白招募到损伤位点，并有助于它们彼此对齐和相互作用，从而提高修复过程的效率。
