View source for 6juq


==mutant PolIV-DNA incoming nucleotide complex 2==
<StructureSection load='6juq' size='340' side='right'caption='[[6juq]], [[Resolution|resolution]] 2.74&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6juq]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6JUQ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6JUQ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.74&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=2TM:5-O-[(S)-HYDROXY{[(S)-HYDROXY(PHOSPHONOOXY)PHOSPHORYL]METHYL}PHOSPHORYL]CYTIDINE'>2TM</scene>, <scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</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=6juq FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6juq OCA], [https://pdbe.org/6juq PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6juq RCSB], [https://www.ebi.ac.uk/pdbsum/6juq PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6juq ProSAT]</span></td></tr>
</table>
== Function ==
[https://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 presence of ribonucleotides in DNA can lead to genomic instability and cellular lethality. To prevent adventitious rNTP incorporation, the majority of the DNA polymerases (dPols) possess a steric filter. The dPol named MsDpo4 (Mycobacterium smegmatis) naturally lacks this steric filter and hence is capable of rNTP addition. The introduction of the steric filter in MsDpo4 did not result in complete abrogation of the ability of this enzyme to incorporate ribonucleotides. In comparison, DNA polymerase IV (PolIV) from Escherichia coli exhibited stringent selection for deoxyribonucleotides. A comparison of MsDpo4 and PolIV led to the discovery of an additional polar filter responsible for sugar selectivity. Thr43 represents the filter in PolIV and this residue forms interactions with the incoming nucleotide to draw it closer to the enzyme surface. As a result, the 2'-OH in rNTPs will clash with the enzyme surface, and therefore ribonucleotides cannot be accommodated in the active site in a conformation compatible with productive catalysis. The substitution of the equivalent residue in MsDpo4-Cys47, with Thr led to a drastic reduction in the ability of the mycobacterial enzyme to incorporate rNTPs. Overall, our studies evince that the polar filter serves to prevent ribonucleotide incorporation by dPols.

A polar filter in DNA polymerases prevents ribonucleotide incorporation.,Johnson MK, Kottur J, Nair DT Nucleic Acids Res. 2019 Nov 18;47(20):10693-10705. doi: 10.1093/nar/gkz792. PMID:31544946<ref>PMID:31544946</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6juq" style="background-color:#fffaf0;"></div>

==See Also==
*[[DNA polymerase 3D structures|DNA polymerase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Johnson MK]]
[[Category: Nair DT]]