2irx

From Proteopedia

Crystal Structure of the Polymerase Domain from Mycobacterium tuberculosis Ligase D with GTP and Manganese.

Structural highlights

2irx is a 1 chain structure with sequence from Mycobacterium tuberculosis H37Rv. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 1.8Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

LIGD_MYCTU With Ku forms a non-homologous end joining (NHEJ) repair enzyme which repairs DNA double-strand breaks (DSB) with reduced fidelity. Recognizes, processes and reseals DSBs, including repairs on incompatible DSB which require 3'-resection, gap filling and ligation. Anneals the 3' overhanging strands from opposing breaks to form a gapped intermediate, which then can be extended in trans by using the termini as primers for extension of the annealed break. Binds to the recessed 5'-phosphate moiety of the downstream DNA strand forming a stable synaptic complex even when the 3'-protruding ends of the template DNA strands are not complementary. Has numerous activities; gap filling copies the template strand, and prefers a 5'-phosphate in the gap and rNTPS (PubMed:17174332, PubMed:17947582), DNA-directed DNA or RNA polymerase on 5'-overhangs, terminal transferase (extending ssDNA or blunt dsDNA in a non-templated fashion, preferentially with rNTPs), DNA-dependent RNA primase (synthesizes short RNAs on unprimed closed ssDNA) and 3'- to 5'-exonuclease on ssDNA (PubMed:15499016). Isolated Pol domain (and presumably the holoenzyme) is able to form complexes between 2 noncompatible protruding 3'-ends DNA ends via microhomologous DNA strands, in a end-bridging function to which it adds a templated nucleotide (PubMed:17947582). Minimal primer length is 2 nucleotides (PubMed:21255731).^[1] ^[2] ^[3] ^[4] The preference of the polymerase domain for rNTPs over dNTPs may be advantageous in dormant cells, where the dNTP pool is limiting. In conjunction with endogenous or Mycobacterium phage Omega Ku (AC Q853W0) can reconstitute NHEJ in Saccharomyces cerevisiae.

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

References

↑ Della M, Palmbos PL, Tseng HM, Tonkin LM, Daley JM, Topper LM, Pitcher RS, Tomkinson AE, Wilson TE, Doherty AJ. Mycobacterial Ku and ligase proteins constitute a two-component NHEJ repair machine. Science. 2004 Oct 22;306(5696):683-5. doi: 10.1126/science.1099824. PMID:15499016 doi:http://dx.doi.org/10.1126/science.1099824
↑ Pitcher RS, Brissett NC, Picher AJ, Andrade P, Juarez R, Thompson D, Fox GC, Blanco L, Doherty AJ. Structure and function of a mycobacterial NHEJ DNA repair polymerase. J Mol Biol. 2007 Feb 16;366(2):391-405. Epub 2006 Oct 20. PMID:17174332 doi:http://dx.doi.org/10.1016/j.jmb.2006.10.046
↑ Brissett NC, Pitcher RS, Juarez R, Picher AJ, Green AJ, Dafforn TR, Fox GC, Blanco L, Doherty AJ. Structure of a NHEJ polymerase-mediated DNA synaptic complex. Science. 2007 Oct 19;318(5849):456-9. PMID:17947582 doi:318/5849/456
↑ Brissett NC, Martin MJ, Pitcher RS, Bianchi J, Juarez R, Green AJ, Fox GC, Blanco L, Doherty AJ. Structure of a Preternary Complex Involving a Prokaryotic NHEJ DNA Polymerase. Mol Cell. 2011 Jan 21;41(2):221-31. PMID:21255731 doi:10.1016/j.molcel.2010.12.026