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==Crystal structure of a single-chain E/F type bilin lyase-isomerase MpeQ==
<StructureSection load='7mc4' size='340' side='right'caption='[[7mc4]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7MC4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7MC4 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]] 2.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MSE:SELENOMETHIONINE'>MSE</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=7mc4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7mc4 OCA], [https://pdbe.org/7mc4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7mc4 RCSB], [https://www.ebi.ac.uk/pdbsum/7mc4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7mc4 ProSAT]</span></td></tr>
</table>
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== Publication Abstract from PubMed ==
Chromophore attachment of the light-harvesting apparatus represents one of the most important post-translational modifications in photosynthetic cyanobacteria. Extensive pigment diversity of cyanobacteria critically depends on bilin lyases that covalently attach chemically distinct chromophores to phycobiliproteins. However, how bilin lyases catalyze bilin ligation reactions and how some lyases acquire additional isomerase abilities remain elusive at the molecular level. Here, we report the crystal structure of a representative bilin lyase-isomerase MpeQ. This structure has revealed a "question-mark" protein architecture that unambiguously establishes the active site conserved among the E/F-type bilin lyases. Based on structural, mutational, and modeling data, we demonstrate that stereoselectivity of the active site plays a critical role in conferring the isomerase activity of MpeQ. We further advance a tyrosine-mediated reaction scheme unifying different types of bilin lyases. These results suggest that lyases and isomerase actions of bilin lyases arise from two coupled molecular events of distinct origin.

Crystal structure and molecular mechanism of an E/F type bilin lyase-isomerase.,Kumarapperuma I, Joseph KL, Wang C, Biju LM, Tom IP, Weaver KD, Grebert T, Partensky F, Schluchter WM, Yang X Structure. 2022 Feb 2. pii: S0969-2126(22)00007-7. doi:, 10.1016/j.str.2022.01.007. PMID:35148828<ref>PMID:35148828</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Kumarapperuma I]]
[[Category: Yang X]]