1l8d
Rad50 coiled-coil Zn hookRad50 coiled-coil Zn hook
Structural highlights
FunctionRAD50_PYRFU Involved in DNA double-strand break repair (DSBR). The Rad50/Mre11 complex possesses single-strand endonuclease activity and ATP-dependent double-strand-specific 3'-5' exonuclease activity. Rad50 provides an ATP-dependent control of Mre11 by unwinding and/or repositioning DNA ends into the Mre11 active site.[HAMAP-Rule:MF_00449] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe Mre11 complex (Mre11 Rad50 Nbs1) is central to chromosomal maintenance and functions in homologous recombination, telomere maintenance and sister chromatid association. These functions all imply that the linked binding of two DNA substrates occurs, although the molecular basis for this process remains unknown. Here we present a 2.2 A crystal structure of the Rad50 coiled-coil region that reveals an unexpected dimer interface at the apex of the coiled coils in which pairs of conserved Cys-X-X-Cys motifs form interlocking hooks that bind one Zn(2+) ion. Biochemical, X-ray and electron microscopy data indicate that these hooks can join oppositely protruding Rad50 coiled-coil domains to form a flexible bridge of up to 1,200 A. This suggests a function for the long insertion in the Rad50 ABC-ATPase domain. The Rad50 hook is functional, because mutations in this motif confer radiation sensitivity in yeast and disrupt binding at the distant Mre11 nuclease interface. These data support an architectural role for the Rad50 coiled coils in forming metal-mediated bridging complexes between two DNA-binding heads. The resulting assemblies have appropriate lengths and conformational properties to link sister chromatids in homologous recombination and DNA ends in non-homologous end-joining. The Rad50 zinc-hook is a structure joining Mre11 complexes in DNA recombination and repair.,Hopfner KP, Craig L, Moncalian G, Zinkel RA, Usui T, Owen BA, Karcher A, Henderson B, Bodmer JL, McMurray CT, Carney JP, Petrini JH, Tainer JA Nature. 2002 Aug 1;418(6897):562-6. PMID:12152085[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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