Schild D, Lio Y C, Collins D W, Tsomondo T, Chen D J
Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
J Biol Chem. 2000 Jun 2;275(22):16443-9. doi: 10.1074/jbc.M001473200.
In yeast, the Rad51-related proteins include Rad55 and Rad57, which form a heterodimer that interacts with Rad51. Five human Rad51 paralogs have been identified (XRCC2, XRCC3, Rad51B/Rad51L1, Rad51C/Rad51L2, and Rad51D/Rad51L3), and each interacts with one or more of the others. Previously we reported that HsRad51 interacts with XRCC3, and Rad51C interacts with XRCC3, Rad51B, and HsRad51. Here we report that in the yeast two-hybrid system, Rad51D interacts with XRCC2 and Rad51C. No other interactions, including self-interactions, were found, indicating that the observed interactions are specific. The yeast Rad51 interacts with human Rad51 and XRCC3, suggesting Rad51 conservation since the human yeast divergence. Data from yeast three-hybrid experiments indicate that a number of the pairs of interactions between human Rad51 paralogs can occur simultaneously. For example, Rad51B expression enhances the binding of Rad51C to XRCC3 and to HsRad51D, and Rad51C expression allows the indirect interaction of Rad51B with Rad51D. Experiments using 6xHis-tagged proteins in the baculovirus system confirm several of our yeast results, including Rad51B interaction with Rad51D only when Rad51C is simultaneously expressed and Rad51C interaction with XRCC2 only when Rad51D is present. These results suggest that these proteins may participate in one complex or multiple smaller ones.
在酵母中，与Rad51相关的蛋白质包括Rad55和Rad57，它们形成一个与Rad51相互作用的异二聚体。已鉴定出五种人类Rad51旁系同源物（XRCC2、XRCC3、Rad51B/Rad51L1、Rad51C/Rad51L2和Rad51D/Rad51L3），且每种都与其他一种或多种相互作用。此前我们报道过HsRad51与XRCC3相互作用，Rad51C与XRCC3、Rad51B和HsRad51相互作用。在此我们报道，在酵母双杂交系统中，Rad51D与XRCC2和Rad51C相互作用。未发现其他相互作用，包括自身相互作用，这表明观察到的相互作用具有特异性。酵母Rad51与人Rad51和XRCC3相互作用，这表明自人类与酵母分化以来Rad51具有保守性。酵母三杂交实验的数据表明，人类Rad51旁系同源物之间的许多相互作用对可以同时发生。例如，Rad51B的表达增强了Rad51C与XRCC3以及与HsRad51D的结合，而Rad51C的表达使Rad51B与Rad51D能够间接相互作用。在杆状病毒系统中使用6xHis标记蛋白进行的实验证实了我们的一些酵母实验结果，包括仅当同时表达Rad51C时Rad51B与Rad51D相互作用，以及仅当存在Rad51D时Rad51C与XRCC2相互作用。这些结果表明，这些蛋白质可能参与一个复合物或多个较小的复合物。
