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5mht

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[[Image:5mht.gif|left|200px]]
 
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==TERNARY STRUCTURE OF HHAI METHYLTRANSFERASE WITH HEMIMETHYLATED DNA AND ADOHCY==
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The line below this paragraph, containing "STRUCTURE_5mht", creates the "Structure Box" on the page.
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<StructureSection load='5mht' size='340' side='right'caption='[[5mht]], [[Resolution|resolution]] 2.70&Aring;' scene=''>
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You may change the PDB parameter (which sets the PDB file loaded into the applet)
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== Structural highlights ==
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or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
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<table><tr><td colspan='2'>[[5mht]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Haemophilus_haemolyticus Haemophilus haemolyticus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5MHT OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5MHT FirstGlance]. <br>
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or leave the SCENE parameter empty for the default display.
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.7&#8491;</td></tr>
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<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=5CM:5-METHYL-2-DEOXY-CYTIDINE-5-MONOPHOSPHATE'>5CM</scene>, <scene name='pdbligand=SAH:S-ADENOSYL-L-HOMOCYSTEINE'>SAH</scene></td></tr>
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{{STRUCTURE_5mht| PDB=5mht | SCENE= }}
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=5mht FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5mht OCA], [https://pdbe.org/5mht PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5mht RCSB], [https://www.ebi.ac.uk/pdbsum/5mht PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5mht ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/MTH1_HAEPH 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.
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/mh/5mht_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=5mht ConSurf].
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<div style="clear:both"></div>
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'''TERNARY STRUCTURE OF HHAI METHYLTRANSFERASE WITH HEMIMETHYLATED DNA AND ADOHCY'''
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==See Also==
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*[[DNA methyltransferase 3D structures|DNA methyltransferase 3D structures]]
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__TOC__
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==Overview==
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</StructureSection>
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The crystal structure of HhaI methyltransferase complexed with non-palindromic duplex DNA, containing a hemimethylated recognition sequence, and with the cofactor analog S-adenosyl-L-homocysteine (AdoHcy), has been determined. The structure provides an explanation for the stronger affinities of DNA methyltransferases for hemimethylated DNA than for unmethylated or fully methylated DNA in the presence of AdoHcy. The unmethylated target 2'-deoxycytidine flips out of the DNA helix and the CH group at position 5 makes van der Waals' contacts with the sulfur atom of AdoHcy. Selectivity/preference for hemimethylated over fully methylated DNA may thus reflect interactions among the chemical substituent (H or CH3) at the C5 position of the flipped cytosine, protein and the bound AdoHcy. The 5-methyl-2'-deoxycytidine on the complementary strand remains in the DNA helix, with the methyl group almost perpendicular to the carboxylate group of Glu239, which is part of the sequence recognition loop. Thus, selectivity/preference for hemimethylated over unmethylated DNA appears to result largely from van der Waals' contacts between the planar Glu239 carboxylate and the methyl group of the 5-methyl-2'-deoxycytidine. Furthermore, the positive electrostatic potential originating from the bound AdoHcy extends to the DNA phosphate groups flanking the flipped cytosine. The increased binding to DNA by long-range electrostatic interactions should also occur with the methyl donor S-adenosyl-L-methionine.
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==About this Structure==
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5MHT is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Haemophilus_haemolyticus Haemophilus haemolyticus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5MHT OCA].
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==Reference==
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A structural basis for the preferential binding of hemimethylated DNA by HhaI DNA methyltransferase., O'Gara M, Roberts RJ, Cheng X, J Mol Biol. 1996 Nov 8;263(4):597-606. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8918941 8918941]
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[[Category: Haemophilus haemolyticus]]
[[Category: Haemophilus haemolyticus]]
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[[Category: Nicotinate N-methyltransferase]]
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[[Category: Large Structures]]
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[[Category: Single protein]]
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[[Category: Cheng X]]
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[[Category: Cheng, X.]]
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[[Category: Methyltransferase]]
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[[Category: Restriction system]]
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[[Category: Transferase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 22:36:04 2008''
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Current revision

TERNARY STRUCTURE OF HHAI METHYLTRANSFERASE WITH HEMIMETHYLATED DNA AND ADOHCY

PDB ID 5mht

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