3FW5: Crystal Structure Of Siderocalin (Ngal, Lipocalin 2) Complexed With Ferric 4-Methyl-Catechol

Citation:
Abstract
The lipocalins are secreted proteins that bind small organic molecules. Scn-Ngal (also known as neutrophil gelatinase associated lipocalin, siderocalin, lipocalin 2) sequesters bacterial iron chelators, called siderophores, and consequently blocks bacterial growth. However, Scn-Ngal is also prominently expressed in aseptic diseases, implying that it binds additional ligands and serves additional functions. Using chemical screens, crystallography and fluorescence methods, we report that Scn-Ngal binds iron together with a small metabolic product called catechol. The formation of the complex blocked the reactivity of iron and permitted its transport once introduced into circulation in vivo. Scn-Ngal then recycled its iron in endosomes by a pH-sensitive mechanism. As catechols derive from bacterial and mammalian metabolism of dietary compounds, the Scn-Ngal-catechol-Fe(III) complex represents an unforeseen microbial-host interaction, which mimics Scn-Ngal-siderophore interactions but instead traffics iron in aseptic tissues. These results identify an endogenous siderophore, which may link the disparate roles of Scn-Ngal in different diseases.
PDB ID: 3FW5Download
MMDB ID: 81815
PDB Deposition Date: 2009/1/16
Updated in MMDB: 2010/08
Experimental Method:
x-ray diffraction
Resolution: 2.3  Å
Source Organism:
Similar Structures:
Biological Unit for 3FW5: monomeric; determined by author
Molecular Components in 3FW5
Label Count Molecule
Protein (1 molecule)
1
Neutrophil Gelatinase-associated Lipocalin(Gene symbol: LCN2)
Molecule annotation
Chemicals (9 molecules)
1
1
2
1
3
3
4
1
5
3
* Click molecule labels to explore molecular sequence information.

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