title: Structure of the bacteriophage T4 DNA adenine methyltransferase.
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.
authors.affiliation: Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, Georgia 30322, USA.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Yang
authors.forename: John R
authors.initials: JR
authors.lastname: Horton
authors.forename: Lan
authors.initials: L
authors.lastname: Zhou
authors.forename: Xu Jia
authors.initials: XJ
authors.lastname: Zhang
authors.forename: Aiping
authors.initials: A
authors.lastname: Dong
authors.forename: Xing
authors.initials: X
authors.lastname: Zhang
authors.forename: Samuel L
authors.initials: SL
authors.lastname: Schlagman
authors.forename: Valeri
authors.initials: V
authors.lastname: Kossykh
authors.forename: Stanley
authors.initials: S
authors.lastname: Hattman
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Cheng
mesh_terms: D000595:Amino Acid Sequence; D017122:Bacteriophage T4 / Q000201:enzymology*; D001665:Binding Sites; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012435:S-Adenosylhomocysteine / Q000378:metabolism; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000737:chemistry* / Q000378:metabolism
chemical_list: D012435:S-Adenosylhomocysteine; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific)