View source for 21cg


==Crystal structure of sulX in complex with FMN and sulfanilamide==
<StructureSection load='21cg' size='340' side='right'caption='[[21cg]], [[Resolution|resolution]] 2.83&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[21cg]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Unclassified_Microbacterium Unclassified Microbacterium]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=21CG OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=21CG 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]] 2.83&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=FMN:FLAVIN+MONONUCLEOTIDE'>FMN</scene>, <scene name='pdbligand=SAN:SULFANILAMIDE'>SAN</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</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=21cg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=21cg OCA], [https://pdbe.org/21cg PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=21cg RCSB], [https://www.ebi.ac.uk/pdbsum/21cg PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=21cg ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A0A482P9Z9_9MICO A0A482P9Z9_9MICO] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The sulfonamide-degrading monooxygenase sulX plays a dual role in bioremediation and antibiotic resistance, yet its molecular mechanism remains elusive. Here we report crystal structures of sulX in its ligand-free form, as an FMN-bound binary complex, and as ternary complexes with six distinct sulfonamides at resolutions ranging from 2.09 to 3.03â¯A. These structures reveal that sulfonamides bind on the re face of the flavin isoalloxazine ring, with their conserved 4-aminophenol and sulfonyl moieties tightly anchored by pi-stacking and hydrogen-bonding interactions, while the divergent aminated substituents extend into an open cleft with minimal specific contacts-a feature that explains the enzyme's remarkable capacity to accommodate diverse sulfonamide substrates. By integrating structural and biochemical data, we propose a catalytic mechanism involving F265-mediated substrate gating and H397-facilitated proton transfer. In addition, structure-based engineering yielded enhanced variants: A399S, which introduces new hydrogen bonds, showed a 37% increase in activity, and P422K achieved a 29% improvement. Our findings establish the structural basis of sulX-mediated sulfonamide degradation and provide a foundation for understanding sulfonamide resistance mechanisms.

Structural insights into sulfonamide degradation by a two-component flavin-dependent monooxygenase.,Hu Y, Liu W, Zhang Q, Gao Z, Zhang H, Li H, Dai L J Hazard Mater. 2026 Sep 15;517:143643. doi: 10.1016/j.jhazmat.2026.143643. PMID:42748825<ref>PMID:42748825</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 21cg" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Unclassified Microbacterium]]
[[Category: Dai LH]]
[[Category: Gao ZD]]
[[Category: Hu YM]]
[[Category: Li H]]
[[Category: Liu WH]]
[[Category: Zhang HL]]
[[Category: Zhang QS]]