This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.

Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.

3khc

From Proteopedia

(Difference between revisions)

Jump to: navigation, search

Revision as of 18:17, 25 December 2014

Crystal Structure of Escherichia coli AlkB in complex with ssDNA containing a 1-methylguanine lesion

Structural highlights

3khc is a 4 chain structure with sequence from Escherichia coli k-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Ligands:	,
NonStd Res:
Related:	3khb
Gene:	aidD, alkB, b2212, JW2200 (Escherichia coli K-12)
Resources:	FirstGlance, OCA, RCSB, PDBsum

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

BACKGROUND: In Escherichia coli, cytotoxic DNA methyl lesions on the N1 position of purines and N3 position of pyrimidines are primarily repaired by the 2-oxoglutarate (2-OG) iron(II) dependent dioxygenase, AlkB. AlkB repairs 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) lesions, but it also repairs 1-methylguanine (1-meG) and 3-methylthymine (3-meT) at a much less efficient rate. How the AlkB enzyme is able to locate and identify methylated bases in ssDNA has remained an open question. METHODOLOGY/PRINCIPAL FINDINGS: We determined the crystal structures of the E. coli AlkB protein holoenzyme and the AlkB-ssDNA complex containing a 1-meG lesion. We coupled this to site-directed mutagenesis of amino acids in and around the active site, and tested the effects of these mutations on the ability of the protein to bind both damaged and undamaged DNA, as well as catalyze repair of a methylated substrate. CONCLUSIONS/SIGNIFICANCE: A comparison of our substrate-bound AlkB-ssDNA complex with our unliganded holoenzyme reveals conformational changes of residues within the active site that are important for binding damaged bases. Site-directed mutagenesis of these residues reveals novel insight into their roles in DNA damage recognition and repair. Our data support a model that the AlkB protein utilizes at least two distinct conformations in searching and binding methylated bases within DNA: a "searching" mode and "repair" mode. Moreover, we are able to functionally separate these modes through mutagenesis of residues that affect one or the other binding state. Finally, our mutagenesis experiments show that amino acid D135 of AlkB participates in both substrate specificity and catalysis.

Structural and mutational analysis of Escherichia coli AlkB provides insight into substrate specificity and DNA damage searching.,Holland PJ, Hollis T PLoS One. 2010 Jan 13;5(1):e8680. PMID:20084272^[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
↑ 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

1 Structural highlights
2 Function
3 Evolutionary Conservation
4 Publication Abstract from PubMed
5 See Also
6 References

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/3khc"

@@ Line 9: / Line 9: @@
 <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3khc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3khc OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3khc RCSB], [http://www.ebi.ac.uk/pdbsum/3khc PDBsum]</span></td></tr>
 </table>
+== Function ==
+[[http://www.uniprot.org/uniprot/ALKB_ECOLI 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).<ref>PMID:12226668</ref> <ref>PMID:12594517</ref> <ref>PMID:16482161</ref> <ref>PMID:19706517</ref> <ref>PMID:21068844</ref> <ref>PMID:20084272</ref>
 == Evolutionary Conservation ==
 [[Image:Consurf_key_small.gif|200px|right]]

3khc

From Proteopedia

Revision as of 18:17, 25 December 2014

Crystal Structure of Escherichia coli AlkB in complex with ssDNA containing a 1-methylguanine lesion

Structural highlights

Function

Evolutionary Conservation

Publication Abstract from PubMed

See Also

References

Contents

Proteopedia Page Contributors and Editors (what is this?)

Views

Personal tools

Navigation

Search

Toolbox