View source for 4irk


==structure of Polymerase-DNA complex, dna==
<StructureSection load='4irk' size='340' side='right' caption='[[4irk]], [[Resolution|resolution]] 2.32&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4irk]] is a 6 chain structure with sequence from [http://en.wikipedia.org/wiki/Ecoli Ecoli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4IRK OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4IRK FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=DCP:2-DEOXYCYTIDINE-5-TRIPHOSPHATE'>DCP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
<tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=DOC:2,3-DIDEOXYCYTIDINE-5-MONOPHOSPHATE'>DOC</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4ir1|4ir1]], [[4ir9|4ir9]], [[4irc|4irc]], [[4ird|4ird]]</td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">b0231, dinB, dinP, JW0221 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=83333 ECOLI])</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=4irk FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4irk OCA], [http://pdbe.org/4irk PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4irk RCSB], [http://www.ebi.ac.uk/pdbsum/4irk PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4irk ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/DPO4_ECOLI DPO4_ECOLI]] Poorly processive, error-prone DNA polymerase involved in untargeted mutagenesis. Copies undamaged DNA at stalled replication forks, which arise in vivo from mismatched or misaligned primer ends. These misaligned primers can be extended by PolIV. Exhibits no 3'-5' exonuclease (proofreading) activity. Overexpression of polIV results in increased frameshift mutagenesis. It is required for stationary-phase adaptive mutation, which provides the bacterium with flexibility in dealing with environmental stress, enhancing long-term survival and evolutionary fitness. May be involved in translesional synthesis, in conjunction with the beta clamp from PolIII.<ref>PMID:9391106</ref> <ref>PMID:11080171</ref> <ref>PMID:11463382</ref> <ref>PMID:11751576</ref> <ref>PMID:12060704</ref>  
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The Y-family DNA polymerase IV or PolIV (Escherichia coli) is the founding member of the DinB family and is known to play an important role in stress-induced mutagenesis. We have determined four crystal structures of this enzyme in its pre-catalytic state in complex with substrate DNA presenting the four possible template nucleotides that are paired with the corresponding incoming nucleotide triphosphates. In all four structures, the Ser42 residue in the active site forms interactions with the base moieties of the incipient Watson-Crick base pair. This residue is located close to the centre of the nascent base pair towards the minor groove. In vitro and in vivo assays show that the fidelity of the PolIV enzyme increases drastically when this Ser residue was mutated to Ala. In addition, the structure of PolIV with the mismatch A:C in the active site shows that the Ser42 residue plays an important role in stabilizing dCTP in a conformation compatible with catalysis. Overall, the structural, biochemical and functional data presented here show that the Ser42 residue is present at a strategic location to stabilize mismatches in the PolIV active site, and thus facilitate the appearance of transition and transversion mutations.

A strategically located serine residue is critical for the mutator activity of DNA polymerase IV from Escherichia coli.,Sharma A, Kottur J, Narayanan N, Nair DT Nucleic Acids Res. 2013 Mar 21. PMID:23525461<ref>PMID:23525461</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4irk" style="background-color:#fffaf0;"></div>

==See Also==
*[[DNA polymerase|DNA polymerase]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: DNA-directed DNA polymerase]]
[[Category: Ecoli]]
[[Category: Nair, D T]]
[[Category: Sharma, A]]
[[Category: Dna polymerase]]
[[Category: Transferase-dna complex]]
[[Category: Y-family]]