Structure of the bacteriophage T4 DNA adenine methyltransferase.
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Yang Z, Horton JR, Zhou L, Zhang XJ, Dong A, Zhang X, Schlagman SL, Kossykh V, Hattman S, Cheng X
Structure of the bacteriophage T4 DNA adenine methyltransferase.
Nat Struct Biol. 2003 Oct;10(10):849-55. Epub 2003 Aug 24.
- PubMed ID
- 12937411 [ View in PubMed]
- Abstract
DNA-adenine methylation at certain GATC sites plays a pivotal role in bacterial and phage gene expression as well as bacterial virulence. We report here the crystal structures of the bacteriophage T4Dam DNA adenine methyltransferase (MTase) in a binary complex with the methyl-donor product S-adenosyl-L-homocysteine (AdoHcy) and in a ternary complex with a synthetic 12-bp DNA duplex and AdoHcy. T4Dam contains two domains: a seven-stranded catalytic domain that harbors the binding site for AdoHcy and a DNA binding domain consisting of a five-helix bundle and a beta-hairpin that is conserved in the family of GATC-related MTase orthologs. Unexpectedly, the sequence-specific T4Dam bound to DNA in a nonspecific mode that contained two Dam monomers per synthetic duplex, even though the DNA contains a single GATC site. The ternary structure provides a rare snapshot of an enzyme poised for linear diffusion along the DNA.