View source for 4k19


==The structure of Human Siderocalin bound to the bacterial siderophore fluvibactin==
<StructureSection load='4k19' size='340' side='right'caption='[[4k19]], [[Resolution|resolution]] 2.74&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4k19]] is a 3 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=4K19 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4K19 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]] 2.74&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=1OD:(4S,5R)-N,N-BIS{3-[(2,3-DIHYDROXYBENZOYL)AMINO]PROPYL}-2-(2,3-DIHYDROXYPHENYL)-5-METHYL-4,5-DIHYDRO-1,3-OXAZOLE-4-CARBOXAMIDE'>1OD</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=FE:FE+(III)+ION'>FE</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</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=4k19 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4k19 OCA], [https://pdbe.org/4k19 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4k19 RCSB], [https://www.ebi.ac.uk/pdbsum/4k19 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4k19 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/NGAL_HUMAN NGAL_HUMAN] Iron-trafficking protein involved in multiple processes such as apoptosis, innate immunity and renal development. Binds iron through association with 2,5-dihydroxybenzoic acid (2,5-DHBA), a siderophore that shares structural similarities with bacterial enterobactin, and delivers or removes iron from the cell, depending on the context. Iron-bound form (holo-24p3) is internalized following binding to the SLC22A17 (24p3R) receptor, leading to release of iron and subsequent increase of intracellular iron concentration. In contrast, association of the iron-free form (apo-24p3) with the SLC22A17 (24p3R) receptor is followed by association with an intracellular siderophore, iron chelation and iron transfer to the extracellular medium, thereby reducing intracellular iron concentration. Involved in apoptosis due to interleukin-3 (IL3) deprivation: iron-loaded form increases intracellular iron concentration without promoting apoptosis, while iron-free form decreases intracellular iron levels, inducing expression of the proapoptotic protein BCL2L11/BIM, resulting in apoptosis. Involved in innate immunity, possibly by sequestrating iron, leading to limit bacterial growth.<ref>PMID:12453413</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The human protein siderocalin (Scn) inhibits bacterial iron acquisition by binding catechol siderophores. Several pathogenic bacteria respond by making stealth siderophores that are not recognized by Scn. Fluvibactin and vibriobactin, respectively of Vibrio fluvialis and Vibrio cholerae , include an oxazoline adjacent to a catechol. This chelating unit binds iron either in a catecholate or a phenolate-oxazoline coordination mode. The latter has been suggested to make vibriobactin a stealth siderophore without directly identifying the coordination mode in relation to Scn binding. We use Scn binding assays with the two siderophores and two oxazoline-substituted analogs and the crystal structure of Fe-fluvibactin:Scn to show that the oxazoline does not prevent Scn binding; hence, vibriobactin is not a stealth siderophore. We show that the phenolate-oxazoline coordination mode is present at physiological pH and is not bound by Scn. However, Scn binding shifts the coordination to the catecholate mode and thereby inactivates this siderophore.

Siderocalin Outwits the Coordination Chemistry of Vibriobactin, a Siderophore of Vibrio cholerae.,Allred BE, Correnti C, Clifton MC, Strong RK, Raymond KN ACS Chem Biol. 2013 Jun 18. PMID:23755875<ref>PMID:23755875</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4k19" style="background-color:#fffaf0;"></div>

==See Also==
*[[Neutrophil gelatinase-associated lipocalin|Neutrophil gelatinase-associated lipocalin]]
*[[Siderocalin 3D structures|Siderocalin 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Clifton MC]]
[[Category: Correnti C]]
[[Category: Strong RK]]