García-Fernández R, Ziegelmüller P, González L, Mansur M, Machado Y, Redecke L, Hahn U, Betzel C, Chávez MDLÁ. Two variants of the major serine protease inhibitor from the sea anemone Stichodactyla helianthus, expressed in Pichia pastoris.
Protein Expr Purif 2016;
123:42-50. [PMID:
26993255 DOI:
10.1016/j.pep.2016.03.003]
[Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 02/26/2016] [Accepted: 03/11/2016] [Indexed: 12/13/2022]
Abstract
The major protease inhibitor from the sea anemone Stichodactyla helianthus (ShPI-1) is a non-specific inhibitor that binds trypsin and other trypsin-like enzymes, as well as chymotrypsin, and human neutrophil elastase. We performed site-directed mutagenesis of ShPI-1 to produce two variants (rShPI-1/K13L and rShPI/Y15S) that were expressed in Pichia pastoris, purified, and characterized. After a single purification step, 65 mg and 15 mg of protein per liter of culture supernatant were obtained for rShPI-1/K13L and rShPI/Y15S, respectively. Functional studies demonstrated a 100-fold decreased trypsin inhibitory activity as result of the K13L substitution at the reactive (P1) site. This protein variant has a novel tight-binding inhibitor activity of pancreatic elastase and increased activity toward neutrophil elastase in comparison to rShPI-1A. In contrast, the substitution Y15S at P2' site did not affect the Ki value against trypsin, but did reduce activity 10-fold against chymotrypsin and neutrophil elastase. Our results provide two new ShPI-1 variants with modified inhibitory activities, one of them with increased biomedical potential. This study also offers new insight into the functional impact of the P1 and P2' sites on ShPI-1 specificity.
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