1svu
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Structure of the Q237W mutant of HhaI DNA methyltransferase: an insight into protein-protein interactions
OverviewOverview
We have determined the structure of a mutant (Q237W) of HhaI DNA, methyltransferase, complexed with the methyl-donor product AdoHcy. The, Q237W mutant proteins were crystallized in the monoclinic space group C2, with two molecules in the crystallographic asymmetric unit., Protein-protein interface calculations in the crystal lattices suggest, that the dimer interface has the specific characteristics for homodimer, protein-protein interactions, while the two active sites are spatially, independent on the outer surface of the dimer. The solution behavior, suggests the formation of HhaI dimers as well. The same HhaI dimer, interface is also observed in the previously characterized binary, (M.HhaI-AdoMet) and ternary (M.HhaI-DNA-AdoHcy) complex structures, crystallized in different space groups. The dimer is characterized either, by a non-crystallographic two-fold symmetry or a crystallographic, symmetry. The dimer interface involves three segments: the amino-terminal, residues 2-8, the carboxy-terminal residues 313-327, and the linker (amino, acids 179-184) between the two functional domains--the catalytic, methylation domain and the DNA target recognition domain. Both the amino-, and carboxy-terminal segments are part of the methylation domain. We also, examined protein-protein interactions of other structurally characterized, DNA MTases, which are often found as a 2-fold related 'dimer' with the, largest dimer interface area for the group-beta MTases. A possible, evolutionary link between the Type I and Type II restriction-modification, systems is discussed.
About this StructureAbout this Structure
1SVU is a Single protein structure of sequence from Haemophilus haemolyticus with SO4, SAH and UNX as ligands. Active as DNA (cytosine-5-)-methyltransferase, with EC number 2.1.1.37 Full crystallographic information is available from OCA.
ReferenceReference
Structure of the Q237W mutant of HhaI DNA methyltransferase: an insight into protein-protein interactions., Dong A, Zhou L, Zhang X, Stickel S, Roberts RJ, Cheng X, Biol Chem. 2004 May;385(5):373-9. PMID:15195996
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