| Structural highlights
Function
[XRCC4_HUMAN] Involved in DNA non-homologous end joining (NHEJ) required for double-strand break repair and V(D)J recombination. Binds to DNA and to DNA ligase IV (LIG4). The LIG4-XRCC4 complex is responsible for the NHEJ ligation step, and XRCC4 enhances the joining activity of LIG4. Binding of the LIG4-XRCC4 complex to DNA ends is dependent on the assembly of the DNA-dependent protein kinase complex DNA-PK to these DNA ends.[1] [2] [3] [4]
Publication Abstract from PubMed
Sarcomeric myosins have the remarkable ability to form regular bipolar thick filaments that, together with actin thin filaments, constitute the fundamental contractile unit of skeletal and cardiac muscle. This has been established for over fifty years and yet a molecular model for the thick filament has not been attained. In part this is due to the lack of a detailed molecular model for the coiled-coil that constitutes the myosin rod. The ability to self-assemble resides in the C-terminal of the section of myosin known as light meromyosin (LMM) which exhibits strong salt dependent aggregation that has inhibited structural studies. Here we evaluate the feasibility of generating a complete model for the myosin rod by combining overlapping structures of five sections of coiled-coil covering 164 amino acid residues which constitute 20% of LMM. Each section contains approximately 7-9 heptads of myosin. The problem of aggregation was overcome by incorporating the globular folding domains, Gp7 and Xrcc4 which enhance crystallization. The effect of these domains on the stability and conformation of the myosin rod was examined through biophysical studies and overlapping structures. In addition, a computational approach was developed to combine the sections into a contiguous model. The structures were aligned, trimmed to form a contiguous model, and simulated for >700 ns to remove the discontinuities and achieve an equilibrated conformation that represents the native state. This experimental and computational strategy lays the foundation for building a model for the entire myosin rod. This article is protected by copyright. All rights reserved.
A composite approach towards a complete model of the myosin rod.,Korkmaz EN, Taylor KC, Andreas MP, Ajay G, Heinze NT, Cui Q, Rayment I Proteins. 2015 Nov 17. doi: 10.1002/prot.24964. PMID:26573747[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Li Z, Otevrel T, Gao Y, Cheng HL, Seed B, Stamato TD, Taccioli GE, Alt FW. The XRCC4 gene encodes a novel protein involved in DNA double-strand break repair and V(D)J recombination. Cell. 1995 Dec 29;83(7):1079-89. PMID:8548796
- ↑ Chen L, Trujillo K, Sung P, Tomkinson AE. Interactions of the DNA ligase IV-XRCC4 complex with DNA ends and the DNA-dependent protein kinase. J Biol Chem. 2000 Aug 25;275(34):26196-205. PMID:10854421 doi:10.1074/jbc.M000491200
- ↑ Nick McElhinny SA, Snowden CM, McCarville J, Ramsden DA. Ku recruits the XRCC4-ligase IV complex to DNA ends. Mol Cell Biol. 2000 May;20(9):2996-3003. PMID:10757784
- ↑ Foster RE, Nnakwe C, Woo L, Frank KM. Monoubiquitination of the nonhomologous end joining protein XRCC4. Biochem Biophys Res Commun. 2006 Mar 3;341(1):175-83. Epub 2006 Jan 6. PMID:16412978 doi:S0006-291X(05)02903-7
- ↑ Korkmaz EN, Taylor KC, Andreas MP, Ajay G, Heinze NT, Cui Q, Rayment I. A composite approach towards a complete model of the myosin rod. Proteins. 2015 Nov 17. doi: 10.1002/prot.24964. PMID:26573747 doi:http://dx.doi.org/10.1002/prot.24964
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