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[[ | ==Ternary complex of Bacillus DNA Polymerase I Large Fragment, DNA duplex, and rCTP in presence of Mg2+== | ||
<StructureSection load='4ds5' size='340' side='right' caption='[[4ds5]], [[Resolution|resolution]] 1.68Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[4ds5]] is a 6 chain structure with sequence from [http://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=4DS5 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4DS5 FirstGlance]. <br> | |||
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr> | |||
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4ds4|4ds4]], [[4dse|4dse]], [[4dsf|4dsf]]</td></tr> | |||
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">polA, GK2730 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=235909 Geobacillus kaustophilus HTA426])</td></tr> | |||
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/DNA-directed_DNA_polymerase DNA-directed DNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.7 2.7.7.7] </span></td></tr> | |||
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4ds5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4ds5 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4ds5 RCSB], [http://www.ebi.ac.uk/pdbsum/4ds5 PDBsum]</span></td></tr> | |||
</table> | |||
<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®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
==See Also== | |||
*[[DNA polymerase|DNA polymerase]] | |||
== | == References == | ||
[[ | <references/> | ||
__TOC__ | |||
== | </StructureSection> | ||
< | |||
[[Category: DNA-directed DNA polymerase]] | [[Category: DNA-directed DNA polymerase]] | ||
[[Category: Geobacillus kaustophilus hta426]] | [[Category: Geobacillus kaustophilus hta426]] | ||
[[Category: Beese, L S | [[Category: Beese, L S]] | ||
[[Category: Wang, W | [[Category: Wang, W]] | ||
[[Category: Dna polymerase i]] | [[Category: Dna polymerase i]] | ||
[[Category: Transferase-dna complex]] | [[Category: Transferase-dna complex]] | ||
Revision as of 17:47, 9 December 2014
Ternary complex of Bacillus DNA Polymerase I Large Fragment, DNA duplex, and rCTP in presence of Mg2+Ternary complex of Bacillus DNA Polymerase I Large Fragment, DNA duplex, and rCTP in presence of Mg2+
Structural highlights
Publication Abstract from PubMedIn 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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