Staphostatins resemble lipocalins, not cystatins in fold.
Staphostatins are the endogenous inhibitors of the major secreted cysteine proteases of Staphylococcus aureus, the staphopains. Here, we present the 1.4 A crystal structure of staphostatin B and show that the fold can be described as a fully closed, highly sheared eight-stranded beta-barrel. Thus, staphostatin B is related to beta-barrel domains that are involved in the inhibition or regulation of proteases of various catalytic types and to the superfamily of lipocalins/cytosolic fatty acid binding proteins. Unexpectedly for a cysteine protease inhibitor, staphostatin B is not significantly similar to cystatins.
D002352:Carrier Proteins / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D015891:Cystatins / Q000737:chemistry*; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D030562:Databases, Protein; D006801:Humans; D054835:Lipocalin 1; D008958:Models, Molecular; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D040681:Structural Homology, Protein
D002352:Carrier Proteins; D015891:Cystatins; C518443:LCN1 protein, human; D054835:Lipocalin 1; D003546:Cysteine Endopeptidases; C479137:staphopain B protein, Staphylococcus aureus