View source for 6g82


==Serum paraoxonase-1 by directed evolution with the L69S/H115W/F222S mutations==
<StructureSection load='6g82' size='340' side='right'caption='[[6g82]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6g82]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6G82 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6G82 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]] 2.401&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</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=6g82 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6g82 OCA], [https://pdbe.org/6g82 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6g82 RCSB], [https://www.ebi.ac.uk/pdbsum/6g82 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6g82 ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Evolutionary trajectories are deemed largely irreversible. In a newly diverged protein, reversion of mutations that led to the functional switch typically results in loss of both the new and ancestral functions. Nonetheless, evolutionary transitions where reversions are viable have also been described. The structural and mechanistic causes of reversion compatibility versus incompatibility therefore remain unclear. We examined two laboratory evolution trajectories of mammalian paraoxonase-1 (PON1), a lactonase with promiscuous organophosphate hydrolase (OPH) activity. Both trajectories began with the same active-site mutant, His115Trp, which lost the native lactonase activity and acquired higher OPH activity. A neo-functionalization trajectory amplified the promiscuous OPH activity, while the re-functionalization trajectory restored the native activity, thus generating a new lactonase that lacks His115. The His115 revertants of these trajectories indicated opposite trends. Revertants of the neo-functionalization trajectory lost both the evolved OPH and the original lactonase activity. Revertants of the trajectory that restored the original lactonase function were, however, fully active. Crystal structures and molecular simulations show that in the newly diverged OPH, the reverted His115 and other catalytic residues are displaced, thus causing loss of both the original and new activity. In contrast, in the re-functionalization trajectory, reversion compatibility of the original lactonase activity derives from mechanistic versatility whereby multiple residues can fulfill the same task. This versatility enables unique sequence-reversible compositions that are inaccessible when the active site was repurposed toward a new function.

Enzyme neo- versus re-functionalization - an epistatic ratchet versus a smooth reversible transition.,Ben-David M, Soskine M, Dubovetskyi A, Cherukuri KP, Dym O, Sussman JL, Liao Q, Szeler K, Kamerlin SCL, Tawfik DS Mol Biol Evol. 2019 Dec 24. pii: 5686393. doi: 10.1093/molbev/msz298. PMID:31873734<ref>PMID:31873734</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6g82" style="background-color:#fffaf0;"></div>

==See Also==
*[[Serum Paraoxonase|Serum Paraoxonase]]
== References ==
<references/>
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Ben-David M]]
[[Category: Sussman JL]]
[[Category: Tawfik DS]]