2ore
From Proteopedia
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[[Image:2ore.gif|left|200px]] | [[Image:2ore.gif|left|200px]] | ||
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'''Binary Structure of Escherichia coli DNA Adenine Methyltransferase and S-adenosylhomocysteine''' | '''Binary Structure of Escherichia coli DNA Adenine Methyltransferase and S-adenosylhomocysteine''' | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Site-specific DNA-methyltransferase (adenine-specific)]] | ||
[[Category: Cheng, X.]] | [[Category: Cheng, X.]] | ||
[[Category: Horton, J R.]] | [[Category: Horton, J R.]] | ||
| - | [[Category: | + | [[Category: Bacterial virulence factor]] |
| - | [[Category: | + | [[Category: Dam methylation]] |
| - | [[Category: | + | [[Category: Gatc recognition]] |
| - | [[Category: | + | [[Category: S-adenosylhomocysteine conformation]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 11:31:00 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 08:31, 4 May 2008
Binary Structure of Escherichia coli DNA Adenine Methyltransferase and S-adenosylhomocysteine
Overview
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)).
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 Page seeded by OCA on Sun May 4 11:31:00 2008
