2ore

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[[Image:2ore.gif|left|200px]]
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{{STRUCTURE_2ore| PDB=2ore | SCENE= }}
{{STRUCTURE_2ore| PDB=2ore | SCENE= }}
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'''Binary Structure of Escherichia coli DNA Adenine Methyltransferase and S-adenosylhomocysteine'''
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===Binary Structure of Escherichia coli DNA Adenine Methyltransferase and S-adenosylhomocysteine===
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==Overview==
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The crystal structure of the Escherichia coli DNA adenine methyltransferase (EcoDam) in a binary complex with the cofactor product S-adenosyl-L-homocysteine (AdoHcy) unexpectedly showed the bound AdoHcy in two alternative conformations, extended or folded. The extended conformation represents the catalytically competent conformation, identical to that of EcoDam-DNA-AdoHcy ternary complex. The folded conformation prevents catalysis, because the homocysteine moiety occupies the target Ade binding pocket. The largest difference between the binary and ternary structures is in the conformation of the N-terminal hexapeptide ((9)KWAGGK(14)). Cofactor binding leads to a strong change in the fluorescence of Trp(10), whose indole ring approaches the cofactor by 3.3A(.) Stopped-flow kinetics and AdoMet cross-linking studies indicate that the cofactor prefers binding to the enzyme after preincubation with DNA. In the presence of DNA, AdoMet binding is approximately 2-fold stronger than AdoHcy binding. In the binary complex the side chain of Lys(14) is disordered, whereas Lys(14) stabilizes the active site in the ternary complex. Fluorescence stopped-flow experiments indicate that Lys(14) is important for EcoDam binding of the extrahelical target base into the active site pocket. This suggests that the hexapeptide couples specific DNA binding (Lys(9)), AdoMet binding (Trp(10)), and insertion of the flipped target base into the active site pocket (Lys(14)).
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(as it appears on PubMed at http://www.pubmed.gov), where 17545164 is the PubMed ID number.
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{{ABSTRACT_PUBMED_17545164}}
==About this Structure==
==About this Structure==
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[[Category: Gatc recognition]]
[[Category: Gatc recognition]]
[[Category: S-adenosylhomocysteine conformation]]
[[Category: S-adenosylhomocysteine conformation]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 11:31:00 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 10:08:43 2008''

Revision as of 07:08, 28 July 2008

Image:2ore.png

Template:STRUCTURE 2ore

Binary Structure of Escherichia coli DNA Adenine Methyltransferase and S-adenosylhomocysteine

Template:ABSTRACT PUBMED 17545164

About this Structure

2ORE is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Two alternative conformations of S-adenosyl-L-homocysteine bound to Escherichia coli DNA adenine methyltransferase and the implication of conformational changes in regulating the catalytic cycle., Liebert K, Horton JR, Chahar S, Orwick M, Cheng X, Jeltsch A, J Biol Chem. 2007 Aug 3;282(31):22848-55. Epub 2007 May 31. PMID:17545164

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