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==Crystal structure of sterol 14-alpha demethylase (CYP51B) from a pathogenic filamentous fungus Aspergillus fumigatus in complex with voriconazole==
<StructureSection load='4uym' size='340' side='right'caption='[[4uym]], [[Resolution|resolution]] 2.55&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4uym]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Aspergillus_fumigatus Aspergillus fumigatus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4UYM OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4UYM 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]] 2.55&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene>, <scene name='pdbligand=VOR:VORICONAZOLE'>VOR</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=4uym FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4uym OCA], [https://pdbe.org/4uym PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4uym RCSB], [https://www.ebi.ac.uk/pdbsum/4uym PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4uym ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CP51B_ASPFU CP51B_ASPFU] Sterol 14alpha-demethylase, encoded by cyp51A and cyp51B, that plays a critical role in the third module of ergosterol biosynthesis pathway, being ergosterol the major sterol component in fungal membranes that participates in a variety of functions (PubMed:18191972, PubMed:26269599, PubMed:26459890, PubMed:29439966, PubMed:9184358). The third module or late pathway involves the ergosterol synthesis itself through consecutive reactions that mainly occur in the endoplasmic reticulum (ER) membrane (By similarity). In filamentous fungi, during the initial step of this module, lanosterol (lanosta-8,24-dien-3beta-ol) can be metabolized to eburicol (PubMed:18191972, PubMed:26459890, PubMed:29439966). Sterol 14alpha-demethylase catalyzes the three-step oxidative removal of the 14alpha-methyl group (C-32) of both these sterols in the form of formate, and converts eburicol and lanosterol to 14-demethyleburicol (4,4,24-trimethylergosta-8,14,24(28)-trienol) and 4,4-dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol, respectively, which are further metabolized by other enzymes in the pathway to ergosterol (PubMed:18191972, PubMed:26269599, PubMed:26459890, PubMed:28461309, PubMed:29439966). Can also use substrates not intrinsic to fungi, such as 24,25-dihydrolanosterol (DHL), producing 4,4'-dimethyl-8,14-cholestadien-3-beta-ol, but at lower rates than the endogenous substrates (By similarity).[UniProtKB:P10614]<ref>PMID:18191972</ref> <ref>PMID:26269599</ref> <ref>PMID:26459890</ref> <ref>PMID:28461309</ref> <ref>PMID:29439966</ref> <ref>PMID:9184358</ref>   As a target of azole drugs, plays a crucial role in azole susceptibility.<ref>PMID:12543662</ref> <ref>PMID:26269599</ref> <ref>PMID:28461309</ref> <ref>PMID:29894182</ref> 
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== Publication Abstract from PubMed ==
Aspergillus fumigatus is the opportunistic fungal pathogen that predominantly affects the immunocompromised population and causes 600,000 deaths per year. The cytochrome P450 (CYP) 51 inhibitor voriconazole is currently the drug of choice, yet the treatment efficiency remains low, calling for rational development of more efficient agents. A. fumigatus has two CYP51 genes, CYP51A and CYP51B, which share 59% amino acid sequence identity. CYP51B is expressed constitutively, while gene CYP51A is reported to be inducible. We expressed, purified, and characterized A. fumigatus CYP51B, including determination of its substrate preferences, catalytic parameters, inhibition, and X-ray structure in complexes with voriconazole and the experimental inhibitor (R)-N-(1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethyl)-4-(5-phenyl-1,3,4-oxadia zol-2-yl)benzamide (VNI). The enzyme demethylated its natural substrate eburicol and the plant CYP51 substrate obtusifoliol at steady-state rates of 17 and 16 min-1, respectively, but did not metabolize lanosterol, and the topical antifungal drug miconazole was the strongest inhibitor that we identified. The X-ray crystal structures displayed high overall similarity of A. fumigatus CYP51B to CYP51 orthologs from other biological kingdoms but revealed phylum-specific differences relevant to enzyme catalysis and inhibition. The complex with voriconazole provides an explanation for the potency of this relatively small molecule, while the complex with VNI outlines a direction for further enhancement of the efficiency of this new inhibitory scaffold to treat humans afflicted with filamentous fungal infections.

Structure-functional Characterization of Cytochrome P450 Sterol 14alpha-Demethylase (CYP51B) from Aspergillus fumigatus and Molecular Basis for the Development of Antifungal Drugs.,Hargrove TY, Wawrzak Z, Lamb DC, Guengerich FP, Lepesheva GI J Biol Chem. 2015 Aug 12. pii: jbc.M115.677310. PMID:26269599<ref>PMID:26269599</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: Aspergillus fumigatus]]
[[Category: Large Structures]]
[[Category: Hargrove TY]]
[[Category: Lepesheva GI]]
[[Category: Wawrzak Z]]