Structure of the bacteriophage T4 DNA adenine methyltransferase.
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.
Yang
Zhe
Z
Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, Georgia 30322, USA.
Horton
John R
JR
Zhou
Lan
L
Zhang
Xu Jia
XJ
Dong
Aiping
A
Zhang
Xing
X
Schlagman
Samuel L
SL
Kossykh
Valeri
V
Hattman
Stanley
S
Cheng
Xiaodong
X
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
D012435:S-Adenosylhomocysteine; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific)