View source for 7sjr


==Cryo-EM structure of AdnA-AdnB(W325A) in complex with DNA and AMPPNP==
<StructureSection load='7sjr' size='340' side='right'caption='[[7sjr]], [[Resolution|resolution]] 3.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[7sjr]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Mycolicibacterium_smegmatis Mycolicibacterium smegmatis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7SJR OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7SJR FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.8&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ANP:PHOSPHOAMINOPHOSPHONIC+ACID-ADENYLATE+ESTER'>ANP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=SF4:IRON/SULFUR+CLUSTER'>SF4</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=7sjr FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7sjr OCA], [https://pdbe.org/7sjr PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7sjr RCSB], [https://www.ebi.ac.uk/pdbsum/7sjr PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7sjr ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/I7FZ56_MYCS2 I7FZ56_MYCS2] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Mycobacterial AdnAB is a heterodimeric helicase-nuclease that initiates homologous recombination by resecting DNA double-strand breaks. The AdnB subunit hydrolyzes ATP to drive single-nucleotide steps of 3'-to-5' translocation of AdnAB on the tracking DNA strand via a ratchet-like mechanism. Trp325 in AdnB motif III, which intercalates into the tracking strand and makes a pi stack on a nucleobase 5' of a flipped-out nucleoside, is the putative ratchet pawl without which ATP hydrolysis is mechanically futile. Here, we report that AdnAB mutants wherein Trp325 was replaced with phenylalanine, tyrosine, histidine, leucine, or alanine retained activity in ssDNA-dependent ATP hydrolysis but displayed a gradient of effects on DSB resection. The resection velocities of Phe325 and Tyr325 mutants were 90% and 85% of the wild-type AdnAB velocity. His325 slowed resection rate to 3% of wild-type and Leu325 and Ala325 abolished DNA resection. A cryo-EM structure of the DNA-bound Ala325 mutant revealed that the AdnB motif III peptide was disordered and the erstwhile flipped out tracking strand nucleobase reverted to a continuous base-stacked arrangement with its neighbors. We conclude that pi stacking of Trp325 on a DNA nucleobase triggers and stabilizes the flipped-out conformation of the neighboring nucleoside that underlies formation of a ratchet pawl.

Structure-activity relationships at a nucleobase-stacking tryptophan required for chemomechanical coupling in the DNA resecting motor-nuclease AdnAB.,Warren GM, Meir A, Wang J, Patel DJ, Greene EC, Shuman S Nucleic Acids Res. 2022 Jan 25;50(2):952-961. doi: 10.1093/nar/gkab1270. PMID:34967418<ref>PMID:34967418</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 7sjr" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Mycolicibacterium smegmatis]]
[[Category: Patel DJ]]
[[Category: Shuman S]]
[[Category: Wang J]]
[[Category: Warren GM]]