de Jager Martijn, Wyman Claire, van Gent Dik C, Kanaar Roland
Department of Cell Biology and Genetics, Erasmus MC, PO Box 1738, 3000 DR Rotterdam, The Netherlands.
Nucleic Acids Res. 2002 Oct 15;30(20):4425-31. doi: 10.1093/nar/gkf574.
The Rad50, Mre11 and Nbs1 complex is involved in many essential chromosomal organization processes dealing with DNA ends, including two major pathways of DNA double-strand break repair, homologous recombination and non-homologous end joining. Previous data on the structure of the human Rad50 and Mre11 (R/M) complex suggest that a common role for the protein complex in these processes is to provide a physical link between DNA ends such that they can be processed in an organized and coordinated manner. Here we describe the DNA binding properties of the R/M complex. The complex bound to both single-stranded and double-stranded DNA. Scanning force microscopy analysis of DNA binding by R/M showed the requirement for an end to form oligomeric R/M complexes, which could then migrate or transfer away from the end. The R/M complex had a lower preference for DNA substrates with 3'-overhangs compared with blunt ends or 5'-overhangs. Interestingly, ATP binding, but not hydrolysis, increased the preference of R/M binding to DNA substrates with 3'-overhangs relative to substrates with blunt ends and 5'-overhangs.
Rad50、Mre11和Nbs1复合物参与许多涉及DNA末端的重要染色体组织过程，包括DNA双链断裂修复的两条主要途径，即同源重组和非同源末端连接。先前关于人类Rad50和Mre11（R/M）复合物结构的数据表明，该蛋白复合物在这些过程中的一个共同作用是在DNA末端之间提供物理连接，以便它们能够以有组织和协调的方式进行处理。在此，我们描述了R/M复合物的DNA结合特性。该复合物与单链和双链DNA均结合。对R/M与DNA结合的扫描力显微镜分析表明，需要一个末端来形成寡聚R/M复合物，然后该复合物可以从末端迁移或转移。与平端或5'突出端相比，R/M复合物对具有3'突出端的DNA底物的偏好性较低。有趣的是，ATP结合而非水解增加了R/M相对于平端和5'突出端底物与具有3'突出端的DNA底物结合的偏好性。
