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Publication Abstract from PubMed

Siderocalin, a member of the lipocalin family of binding proteins, is found in neutrophil granules, uterine secretions, and at markedly elevated levels in serum and synovium during bacterial infection; it is also secreted from epithelial cells in response to inflammation or tumorigenesis. Identification of high-affinity ligands, bacterial catecholate-type siderophores (such as enterochelin), suggested a possible function for siderocalin: an antibacterial agent, complementing the general antimicrobial innate immune system iron-depletion strategy, sequestering iron as ferric siderophore complexes. Supporting this hypothesis, siderocalin is a potent bacteriostatic agent in vitro under iron-limiting conditions and, when knocked out, renders mice remarkably susceptible to bacterial infection. Here we show that siderocalin also binds soluble siderophores of mycobacteria, including M. tuberculosis: carboxymycobactins. Siderocalin employs a degenerate recognition mechanism to cross react with these dissimilar types of siderophores, broadening the potential utility of this innate immune defense.

Siderocalin (Lcn 2) also binds carboxymycobactins, potentially defending against mycobacterial infections through iron sequestration.,Holmes MA, Paulsene W, Jide X, Ratledge C, Strong RK Structure. 2005 Jan;13(1):29-41. PMID:15642259^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.