Secreted aspartic proteases (Saps) of pathogenic Candida spp. represent a specific target for antifungal drug development. We synthesized a series of peptidomimetic inhibitors with different isosteric groups and modifications at individual positions and tested them with purified Saps from C. albicans (Sap2p), C. tropicalis (Sapt1p), and C. parapsilosis (Sapp1p). The kinetic parameters indicated that all three proteases prefer binding of inhibitors containing bulky hydrophobic residues between positions P3 and P3'. The most divergent specificity was found for Sapp1p. The sequence alignment of Sap2p, Sapt1p, and Sapp1p, and homology modeling of Sapp1p with the crystal structure of Sapt1p and the complex of Sap2p with a peptidomimetic inhibitor showed that the overall folds of Sap2p, Sapt1p, and Sapp1p are similar. However, the N- and C-terminal loops formed by disulfide bonds between residues 47-53 and 258-292 are significantly shorter in Sapp1p, and a unique insertion following Tyr 129 in Sapp1p results in the formation of a loop that can interact with inhibitor residues. These Sapp1p structural differences might lead to its altered susceptibility to inhibition.
- MeSH
- Aspartic Acid Endopeptidases chemistry drug effects MeSH
- Candida enzymology MeSH
- Financing, Organized MeSH
- Protease Inhibitors pharmacology chemical synthesis chemistry MeSH
- Isoenzymes chemistry drug effects MeSH
- Molecular Conformation MeSH
- Models, Molecular MeSH
- Molecular Sequence Data MeSH
- Amino Acid Sequence MeSH
- Sequence Homology, Amino Acid MeSH
- Stereoisomerism MeSH
- Substrate Specificity MeSH
- Protein Structure, Tertiary MeSH
- Structure-Activity Relationship MeSH
The specificity of the proteinase of myeloblastosis-associated virus (MAV) was studied with (a) 21 substrate-based inhibitors, (b) 9 inhibitors with pseudopalindrome sequences, (c) 8 chimeric inhibitors, and (d) 3 compounds designed as human immunodeficiency virus 1 (HIV-1) proteinase inhibitors. The central inhibitory unit (transition state or cleaved bond analog) and the role of the inhibitor side chains from P4 to P4' were investigated. MAV proteinase prefers an aromatic side chain in P1 and a small aliphatic nonpolar chain in P2 and P2'. Residues in P5 and P4 positions are outside of the short catalytic cleft of the enzyme, but still influence binding considerably. The data obtained provide evidence that the MAV proteinase has generally lower specificity and poorer binding than the HIV proteinase.
- MeSH
- Aspartic Acid Endopeptidases * antagonists & inhibitors MeSH
- HIV-1 enzymology MeSH
- HIV Protease metabolism MeSH
- Protease Inhibitors pharmacology chemical synthesis MeSH
- Kinetics MeSH
- Molecular Sequence Data MeSH
- Oligopeptides pharmacology chemical synthesis MeSH
- Amino Acid Sequence MeSH
- Substrate Specificity MeSH
- Avian Myeloblastosis Virus * enzymology MeSH
- Structure-Activity Relationship MeSH
- Publication type
- Comparative Study MeSH
- MeSH
- Aspartic Acid Endopeptidases genetics metabolism MeSH
- HIV Protease metabolism MeSH
- Kinetics MeSH
- Molecular Sequence Data MeSH
- Mutagenesis, Site-Directed MeSH
- Oligopeptides chemistry MeSH
- Protein Engineering MeSH
- Amino Acid Sequence MeSH
- Substrate Specificity MeSH
- Avian Myeloblastosis Virus * enzymology genetics MeSH
