Primary Citation of Related Structures: 1FY1, 1FY3
PubMed Abstract:
Heparin binding protein (HBP) is an inactive serine protease homologue with important implications in host defense during infections and inflammations. Two mutants of human HBP, [R23S,F25E]HBP and [G175Q]HBP, have been produced to investigate structure-function relationships of residues in the putative lipid A/lipopolysaccharide (LPS) binding site and BPTI (bovine pancreatic trypsin inhibitor) binding site ...
Heparin binding protein (HBP) is an inactive serine protease homologue with important implications in host defense during infections and inflammations. Two mutants of human HBP, [R23S,F25E]HBP and [G175Q]HBP, have been produced to investigate structure-function relationships of residues in the putative lipid A/lipopolysaccharide (LPS) binding site and BPTI (bovine pancreatic trypsin inhibitor) binding site. The X-ray structures have been determined at 1.9 A resolution for [G175Q]HBP and at 2.5 A resolution for the [R23S,F25E]HBP mutant, and the structures have been fully refined to R-factors of 18.2 % and 20.7 %, respectively. The G175Q mutation does not alter the overall structure of the protein, but the ability to bind BPTI has been eliminated, and the mutant mediates only a limited stimulation of the LPS-induced cytokine release from human monocytes. The lipid A/LPS binding property of [G175Q]HBP is comparable with that of native HBP. The R23S,F25E mutations do not affect the binding of lipid A/LPS and BPTI or the LPS-induced cytokine release from human monocytes. This shows that two diverse ligands, lipid A/LPS and BPTI, do not share binding sites. Previously, there was convincing evidence for the proposed lipid A/LPS binding site of HBP. Unexpectedly, the extensive structural changes introduced by mutation of Arg23 and Phe25 do not affect the binding of lipid A/LPS, indicating that another not yet identified site on HBP is involved in the binding of lipid A/LPS.
Related Citations:
Atomic resolution structure of human HBP/CAP37/Azurocidin Karlsen, S., Iversen, L.F., Larsen, I.K., Flodgaard, H.J., Kastrup, J.S. (1998) Acta Crystallogr D Biol Crystallogr 54: 598
Structure of HBP, a multifunctional protein with a serine proteinase fold Iversen, L.F., Kastrup, J.S., Bjorn, S.E., Rasmussen, P.B., Wiberg, F.C., Flodgaard, H.J., Larsen, I.K. (1997) Nat Struct Biol 4: 265
Crystallization and Molecular Replacement Solution of Human Heparin Binding Protein Iversen, L.F., Kastrup, J.S., Larsen, I.K., Bjorn, S.E., Rasmussen, P.B., Wiberg, F.C., Flodgaard, H.J. (1996) Acta Crystallogr D Biol Crystallogr 52: 1222
Structure and function of the N-linked glycans of HBP/CAP37/azurocidin: Crystal structure determination and biological characterization of nonglycosylated HBP Iversen, L.F., Kastrup, J.S., Bjorn, S.E., Wiberg, F.C., Larsen, I.K., Flodgaard, H.J., Rasmussen, P.B. (1999) Protein Sci 8: 2019
Organizational Affiliation:
Department of Medicinal Chemistry, Royal Danish School of Pharmacy, Copenhagen, Denmark. kastrup@medchem.dfh.dk
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