Send to

Choose Destination
J Biol Chem. 2016 Dec 9;291(50):25901-25910. Epub 2016 Oct 25.

Human Metabolome-derived Cofactors Are Required for the Antibacterial Activity of Siderocalin in Urine.

Author information

From the Division of Infectious Diseases, Department of Medicine.
the Center for Women's Infectious Diseases Research, and.
the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
the Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington 98195, and.
the Department of Chemistry, Washington University, St. Louis, Missouri 63130.
From the Division of Infectious Diseases, Department of Medicine,


In human urinary tract infections, host cells release the antimicrobial protein siderocalin (SCN; also known as lipocalin-2, neutrophil gelatinase-associated lipocalin, or 24p3) into the urinary tract. By binding to ferric catechol complexes, SCN can sequester iron, a growth-limiting nutrient for most bacterial pathogens. Recent evidence links the antibacterial activity of SCN in human urine to iron sequestration and metabolomic variation between individuals. To determine whether these metabolomic associations correspond to functional Fe(III)-binding SCN ligands, we devised a biophysical protein binding screen to identify SCN ligands through direct analysis of human urine. This screen revealed a series of physiologic unconjugated urinary catechols that were able to function as SCN ligands of which pyrogallol in particular was positively associated with high urinary SCN activity. In a purified, defined culture system, these physiologic SCN ligands were sufficient to activate SCN antibacterial activity against Escherichia coli In the presence of multiple SCN ligands, native mass spectrometry demonstrated that SCN may preferentially combine different ligands to coordinate iron, suggesting that availability of specific ligand combinations affects in vivo SCN antibacterial activity. These results support a mechanistic link between the human urinary metabolome and innate immune function.


Escherichia coli (E. coli); NGAL; host-pathogen interaction; infectious disease; iron; lipocalin 2; mass spectrometry (MS); siderocalin; siderophore; urinary tract infection

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center