000008412 001__ 8412
000008412 005__ 20250218124626.0
000008412 02470 $$ahttps://doi.org/10.1371/journal.pone.0087074$$2doi
000008412 037__ $$aTEXTUAL
000008412 037__ $$bArticle
000008412 041__ $$aeng
000008412 245__ $$aFactors That Control the Chemistry of the LOV Domain Photocycle
000008412 269__ $$a2014-01-27
000008412 336__ $$aArticle
000008412 520__ $$a&lt;p&gt;Algae, plants, bacteria and fungi contain Light-Oxygen-Voltage (LOV) domains that function as blue light sensors to control cellular responses to light. All LOV domains contain a bound flavin chromophore that is reduced upon photon absorption and forms a reversible, metastable covalent bond with a nearby cysteine residue. In &lt;em&gt;Avena sativa&lt;/em&gt; LOV2 (&lt;em&gt;As&lt;/em&gt;LOV2), the photocycle is accompanied by an allosteric conformational change that activates the attached phototropin kinase in the full-length protein. Both the conformational change and formation of the cysteinyl-flavin adduct are stabilized by the reduction of the N5 atom in the flavin’s isoalloxazine ring. In this study, we perform a mutational analysis to investigate the requirements for LOV2 to photocycle. We mutated all the residues that interact with the chromophore isoalloxazine ring to inert functional groups but none could fully inhibit the photocycle except those to the active-site cysteine. However, electronegative side chains in the vicinity of the chromophore accelerate the N5 deprotonation and the return to the dark state. Mutations to the N414 and Q513 residues identify a potential water gate and H&lt;sub&gt;2&lt;/sub&gt;O coordination sites. These residues affect the electronic nature of the chromophore and photocycle time by helping catalyze the N5 reduction leading to the completion of the photocycle. In addition, we demonstrate that dehydration leads to drastically slower photocycle times. Finally, to investigate the requirements of an active-site cysteine for photocycling, we moved the nearby cysteine to alternative locations and found that some variants can still photocycle. We propose a new model of the LOV domain photocycle that involves all of these components.&lt;/p&gt;
000008412 536__ $$oNational Institutes of Health$$cGM088668
000008412 536__ $$oNational Institutes of Health$$c5T32GM007183-34
000008412 536__ $$oChicago Biomedical Consortium
000008412 536__ $$oChicago Community Trust$$aThe Searle Funds
000008412 540__ $$a&lt;p&gt;© 2014 Zayner, Sosnick. &lt;/p&gt; &lt;p&gt;This is an open-access article distributed under the terms of the &lt;a href="http://creativecommons.org/licenses/by/4.0/"&gt;Creative Commons Attribution License&lt;/a&gt;, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.&lt;/p&gt;
000008412 542__ $$fCC BY
000008412 690__ $$aBiological Sciences Division
000008412 691__ $$aBiochemistry and Molecular Biology
000008412 7001_ $$aZayner, Josiah P.$$uUniversity of Chicago
000008412 7001_ $$aSosnick, Tobin R.$$uUniversity of Chicago
000008412 773__ $$tPLOS ONE
000008412 8564_ $$yArticle$$9a99e696e-9ea7-4f08-bfc2-db91823a4b68$$s1505729$$uhttps://knowledge.uchicago.edu/record/8412/files/journal.pone.0087074.pdf$$ePublic
000008412 909CO $$ooai:uchicago.tind.io:8412$$pGLOBAL_SET
000008412 983__ $$aArticle