| Structural highlights
2fdk is a 2 chain structure with sequence from Ecoli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Ligands: | , , |
| NonStd Res: | |
| Related: | 2fd8, 2fdf, 2fdg, 2fdh, 2fdi, 2fdj |
| Gene: | alkB, aidD (ECOLI) |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT, TOPSAN |
Function
[ALKB_ECOLI] Dioxygenase that repairs alkylated DNA and RNA containing 3-methylcytosine or 1-methyladenine by oxidative demethylation. Has highest activity towards 3-methylcytosine. Has lower activity towards alkylated DNA containing ethenoadenine, and no detectable activity towards 1-methylguanine or 3-methylthymine. Accepts double-stranded and single-stranded substrates. Requires molecular oxygen, alpha-ketoglutarate and iron. Provides extensive resistance to alkylating agents such as MMS and DMS (SN2 agents), but not to MMNG and MNU (SN1 agents).[1] [2] [3] [4] [5] [6]
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 PubMed
Nucleic acid damage by environmental and endogenous alkylation reagents creates lesions that are both mutagenic and cytotoxic, with the latter effect accounting for their widespread use in clinical cancer chemotherapy. Escherichia coli AlkB and the homologous human proteins ABH2 and ABH3 (refs 5, 7) promiscuously repair DNA and RNA bases damaged by S(N)2 alkylation reagents, which attach hydrocarbons to endocyclic ring nitrogen atoms (N1 of adenine and guanine and N3 of thymine and cytosine). Although the role of AlkB in DNA repair has long been established based on phenotypic studies, its exact biochemical activity was only elucidated recently after sequence profile analysis revealed it to be a member of the Fe-oxoglutarate-dependent dioxygenase superfamily. These enzymes use an Fe(II) cofactor and 2-oxoglutarate co-substrate to oxidize organic substrates. AlkB hydroxylates an alkylated nucleotide base to produce an unstable product that releases an aldehyde to regenerate the unmodified base. Here we have determined crystal structures of substrate and product complexes of E. coli AlkB at resolutions from 1.8 to 2.3 A. Whereas the Fe-2-oxoglutarate dioxygenase core matches that in other superfamily members, a unique subdomain holds a methylated trinucleotide substrate into the active site through contacts to the polynucleotide backbone. Amide hydrogen exchange studies and crystallographic analyses suggest that this substrate-binding 'lid' is conformationally flexible, which may enable docking of diverse alkylated nucleotide substrates in optimal catalytic geometry. Different crystal structures show open and closed states of a tunnel putatively gating O2 diffusion into the active site. Exposing crystals of the anaerobic Michaelis complex to air yields slow but substantial oxidation of 2-oxoglutarate that is inefficiently coupled to nucleotide oxidation. These observations suggest that protein dynamics modulate redox chemistry and that a hypothesized migration of the reactive oxy-ferryl ligand on the catalytic Fe ion may be impeded when the protein is constrained in the crystal lattice.
Crystal structures of catalytic complexes of the oxidative DNA/RNA repair enzyme AlkB.,Yu B, Edstrom WC, Benach J, Hamuro Y, Weber PC, Gibney BR, Hunt JF Nature. 2006 Feb 16;439(7078):879-84. PMID:16482161[7]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Falnes PO, Johansen RF, Seeberg E. AlkB-mediated oxidative demethylation reverses DNA damage in Escherichia coli. Nature. 2002 Sep 12;419(6903):178-82. PMID:12226668 doi:10.1038/nature01048
- ↑ Aas PA, Otterlei M, Falnes PO, Vagbo CB, Skorpen F, Akbari M, Sundheim O, Bjoras M, Slupphaug G, Seeberg E, Krokan HE. Human and bacterial oxidative demethylases repair alkylation damage in both RNA and DNA. Nature. 2003 Feb 20;421(6925):859-63. PMID:12594517 doi:10.1038/nature01363
- ↑ Yu B, Edstrom WC, Benach J, Hamuro Y, Weber PC, Gibney BR, Hunt JF. Crystal structures of catalytic complexes of the oxidative DNA/RNA repair enzyme AlkB. Nature. 2006 Feb 16;439(7078):879-84. PMID:16482161 doi:10.1038/nature04561
- ↑ Yu B, Hunt JF. Enzymological and structural studies of the mechanism of promiscuous substrate recognition by the oxidative DNA repair enzyme AlkB. Proc Natl Acad Sci U S A. 2009 Aug 25;106(34):14315-20. Epub 2009 Aug 11. PMID:19706517
- ↑ Yi C, Jia G, Hou G, Dai Q, Zhang W, Zheng G, Jian X, Yang CG, Cui Q, He C. Iron-catalysed oxidation intermediates captured in a DNA repair dioxygenase. Nature. 2010 Nov 11;468(7321):330-3. PMID:21068844 doi:10.1038/nature09497
- ↑ Holland PJ, Hollis T. Structural and mutational analysis of Escherichia coli AlkB provides insight into substrate specificity and DNA damage searching. PLoS One. 2010 Jan 13;5(1):e8680. PMID:20084272 doi:10.1371/journal.pone.0008680
- ↑ Yu B, Edstrom WC, Benach J, Hamuro Y, Weber PC, Gibney BR, Hunt JF. Crystal structures of catalytic complexes of the oxidative DNA/RNA repair enzyme AlkB. Nature. 2006 Feb 16;439(7078):879-84. PMID:16482161 doi:10.1038/nature04561
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