Document Detail


Engineering the substrate specificity of rhizopuspepsin: the role of Asp 77 of fungal aspartic proteinases in facilitating the cleavage of oligopeptide substrates with lysine in P1.
MedLine Citation:
PMID:  7613467     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Rhizopuspepsin and other fungal aspartic proteinases are distinct from the mammalian enzymes in that they are able to cleave substrates with lysine in the P1 position. Sequence and structural comparisons suggest that two aspartic acid residues, Asp 30 and Asp 77 (pig pepsin numbering), may be responsible for generating this unique specificity. Asp 30 and Asp 77 were changed to the corresponding residues in porcine pepsin, Ile 30 and Thr 77, to create single and double mutants. The zymogen forms of the wild-type and mutant enzymes were overexpressed in Escherichia coli as inclusion bodies. Following solubilization, denaturation, refolding, activation, and purification to homogeneity, structural and kinetic comparisons were made. The mutant enzymes exhibited a high degree of structural similarity to the wild-type recombinant protein and a native isozyme. The catalytic activities of the recombinant proteins were analyzed with chromogenic substrates containing lysine in the P1, P2, or P3 positions. Mutation of Asp 77 resulted in a loss of 7 kcal mol-1 of transition-state stabilization energy in the hydrolysis of the substrate containing lysine in P1. An inhibitor containing the positively charged P1-lysine side chain inhibited only the enzymes containing Asp 77. Inhibition of the Asp 77 mutants of rhizopuspepsin and several mammalian enzymes was restored upon acetylation of the lysine side chain. These results suggest that an exploitation of the specific electrostatic interaction of Asp 77 in the active site of fungal enzymes may lead to the design of compounds that preferentially inhibit a variety of related Candida proteinases in immunocompromised patients.
Authors:
W T Lowther; P Majer; B M Dunn
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Protein science : a publication of the Protein Society     Volume:  4     ISSN:  0961-8368     ISO Abbreviation:  Protein Sci.     Publication Date:  1995 Apr 
Date Detail:
Created Date:  1995-08-24     Completed Date:  1995-08-24     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  9211750     Medline TA:  Protein Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  689-702     Citation Subset:  IM    
Affiliation:
Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville 32610-0245, USA.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Sequence
Animals
Aspartic Acid / chemistry*
Aspartic Acid Endopeptidases / antagonists & inhibitors,  chemistry,  genetics,  metabolism*
Base Sequence
Circular Dichroism
Computer Graphics
Enzyme Inhibitors / pharmacology
Enzyme Precursors / metabolism
Hydrogen Bonding
Hydrogen-Ion Concentration
Kinetics
Models, Molecular
Molecular Sequence Data
Mutagenesis, Site-Directed
Oligopeptides / metabolism*
Pepsin A / chemistry
Protein Denaturation
Protein Engineering*
Protein Folding
Recombinant Proteins / chemistry,  metabolism
Substrate Specificity
Swine
Grant Support
ID/Acronym/Agency:
DK18865/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Enzyme Inhibitors; 0/Enzyme Precursors; 0/Oligopeptides; 0/Recombinant Proteins; 56-84-8/Aspartic Acid; EC 3.4.23.-/Aspartic Acid Endopeptidases; EC 3.4.23.1/Pepsin A; EC 3.4.23.21/rhizopuspepsin
Comments/Corrections

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


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