View source for 4dqq


==Ternary complex of Bacillus DNA Polymerase I Large Fragment E658A, DNA duplex, and rCTP (paired with dG of template) in presence of Mg2+==
<StructureSection load='4dqq' size='340' side='right'caption='[[4dqq]], [[Resolution|resolution]] 1.59&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4dqq]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Geobacillus_kaustophilus_HTA426 Geobacillus kaustophilus HTA426]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4DQQ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4DQQ FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CTP:CYTIDINE-5-TRIPHOSPHATE'>CTP</scene>, <scene name='pdbligand=DOC:2,3-DIDEOXYCYTIDINE-5-MONOPHOSPHATE'>DOC</scene>, <scene name='pdbligand=MES:2-(N-MORPHOLINO)-ETHANESULFONIC+ACID'>MES</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=MPD:(4S)-2-METHYL-2,4-PENTANEDIOL'>MPD</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4dqq FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4dqq OCA], [https://pdbe.org/4dqq PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4dqq RCSB], [https://www.ebi.ac.uk/pdbsum/4dqq PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4dqq ProSAT]</span></td></tr>
</table>
== Function ==
[[https://www.uniprot.org/uniprot/Q5KWC1_GEOKA Q5KWC1_GEOKA]] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
In addition to discriminating against base-pair mismatches, DNA polymerases exhibit a high degree of selectivity for deoxyribonucleotides over ribo- or dideoxy nucleotides. It has been proposed that a single active site residue (steric gate) blocks productive binding of nucleotides containing 2' hydroxyls. Although this steric gate plays a role in sugar moiety discrimination, its interactions do not account fully for the observed behavior of mutants. Here we present ten high-resolution crystal structures and enzyme kinetic analyses of Bacillus DNA polymerase I large fragment (BF) variants complexed with deoxy-, ribo-, dideoxy-nucleotides, and a DNA substrate. Taken together, these data present a more nuanced and general mechanism for nucleotide discrimination in which ensembles of intermediate conformations in the active site trap non-cognate substrates. It is known that the active site O-helix transitions from an open state in the absence of nucleotide substrates to a ternary complex closed state in which the reactive groups are aligned for catalysis. Substrate misalignment in the closed state plays a fundamental part in preventing non-cognate nucleotide misincorpation. The structures presented here show that additional O-helix conformations intermediate between the open and closed state extremes create an ensemble of binding sites that trap and misalign non-cognate nucleotides. Water-mediated interactions, absent in the fully closed state, play an important role in formation of these binding sites, and can be remodeled to accommodate different non-cognate substrates. This mechanism may extend also to base-pair discrimination.

Structural factors that determine selectivity of a high-fidelity DNA polymerase for deoxy-, dideoxy-, and ribo-nucleotides.,Wang W, Wu EY, Hellinga HW, Beese LS J Biol Chem. 2012 May 30. PMID:22648417<ref>PMID:22648417</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4dqq" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Geobacillus kaustophilus HTA426]]
[[Category: Large Structures]]
[[Category: Beese LS]]
[[Category: Wang W]]