1fjx

STRUCTURE OF TERNARY COMPLEX OF HHAI METHYLTRANSFERASE MUTANT (T250G) IN COMPLEX WITH DNA AND ADOHCY

spinqualitylabelsall models 1fjx, resolution 2.26Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1fjx is a 3 chain structure with sequence from "bacillus_x"_pritchett_and_stillman_1919 "bacillus x" pritchett and stillman 1919. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: SAH, SO4 Related: 3mht Activity: DNA (cytosine-5-)-methyltransferase, with EC number 2.1.1.37 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [MTH1_HAEPH] This methylase recognizes the double-stranded sequence GCGC, causes specific methylation on C-2 on both strands, and protects the DNA from cleavage by the HhaI endonuclease. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed DNA cytosine-5-methyltransferase HhaI recognizes the GCGC sequence and flips the inner cytosine out of DNA helix and into the catalytic site for methylation. The 5'-phosphate of the flipped out cytosine is in contact with the conserved Thr-250 from the target recognition domain. We have produced 12 mutants of Thr-250 and examined their methylation potential in vivo. Six active mutants were subjected to detailed biochemical and structural studies. Mutants with similar or smaller side chains (Ser, Cys, and Gly) are very similar to wild-type enzyme in terms of steady-state kinetic parameters k(cat), K(m)(DNA), K(m)(AdoMet). In contrast, the mutants with bulkier side chains (Asn, Asp, and His) show increased K(m) values for both substrates. Fluorescence titrations and stopped-flow kinetic analysis of interactions with duplex oligonucleotides containing 2-aminopurine at the target base position indicate that the T250G mutation leads to a more polar but less solvent-accessible position of the flipped out target base. The x-ray structure of the ternary M. HhaI(T250G).DNA.AdoHcy complex shows that the target cytosine is locked in the catalytic center of enzyme. The space created by the mutation is filled by water molecules and the adjacent DNA backbone atoms dislocate slightly toward the missing side chain. In aggregate, our results suggest that the side chain of Thr-250 is involved in constraining the conformation the DNA backbone and the target base during its rotation into the catalytic site of enzyme. Functional roles of the conserved threonine 250 in the target recognition domain of HhaI DNA methyltransferase.,Vilkaitis G, Dong A, Weinhold E, Cheng X, Klimasauskas S J Biol Chem. 2000 Dec 8;275(49):38722-30. PMID:11102456 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also DNA methyltransferase 3D structures

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