2qm4: Difference between revisions

The recently characterised 299-residue human XLF/Cernunnos protein plays a crucial role in DNA repair by non-homologous end joining (NHEJ) and interacts with the XRCC4-DNA Ligase IV complex. Here, we report the crystal structure of the XLF (1-233) homodimer at 2.3 A resolution, confirming the predicted structural similarity to XRCC4. The XLF coiled-coil, however, is shorter than that of XRCC4 and undergoes an unexpected reverse in direction giving rise to a short distorted four helical bundle and a C-terminal helical structure wedged between the coiled-coil and head domain. The existence of a dimer as the major species is confirmed by size-exclusion chromatography, analytical ultracentrifugation, small-angle X-ray scattering and other biophysical methods. We show that the XLF structure is not easily compatible with a proposed XRCC4:XLF heterodimer. However, we demonstrate interactions between dimers of XLF and XRCC4 by surface plasmon resonance and analyse these in terms of surface properties, amino-acid conservation and mutations in immunodeficient patients. Our data are most consistent with head-to-head interactions in a 2:2:1 XRCC4:XLF:Ligase IV complex.

Crystal structure of human XLF/Cernunnos reveals unexpected differences from XRCC4 with implications for NHEJ., Li Y, Chirgadze DY, Bolanos-Garcia VM, Sibanda BL, Davies OR, Ahnesorg P, Jackson SP, Blundell TL, EMBO J. 2008 Jan 9;27(1):290-300. Epub 2007 Nov 29. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=18046455 18046455]

[[Category: Blundell, T L.]]

[[Category: Bolanos-Garcia, V M.]]

[[Category: Chirgadze, D Y.]]

[[Category: Davies, O R.]]

[[Category: Sibanda, B L.]]

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