title: Inhibition of a cathepsin L-like cysteine protease by a chimeric propeptide-derived inhibitor.
abstract: Like other papain-related cathepsins, congopain from Trypanosoma congolense is synthesized as a zymogen. We have previously identified a proregion-derived peptide (Pcp27), acting as a weak and reversible inhibitor of congopain. Pcp27 contains a 5-mer YHNGA motif, which is essential for selectivity in the inhibition of its mature form [Lalmanach, G., Lecaille, F., Chagas, J. R., Authié, E., Scharfstein, J., Juliano, M. A., and Gauthier, F. (1998) J. Biol. Chem. 273, 25112-25116]. In the work presented here, a homology model of procongopain was generated and subsequently used to model a chimeric 50-mer peptide (called H3-Pcp27) corresponding to the covalent linkage of an unrelated peptide (H3 helix from Antennapedia) to Pcp27. Molecular simulations suggested that H3-Pcp27 (pI = 9.99) maintains an N-terminal helical conformation, and establishes more complementary electrostatic interactions (E(coul) = -25.77 kcal/mol) than 16N-Pcp27, the 34-mer Pcp27 sequence plus the 16 native residues upstream from the proregion (E(coul) = 0.20 kcal/mol), with the acid catalytic domain (pI = 5.2) of the mature enzyme. In silico results correlated with the significant improvement of congopain inhibition by H3-Pcp27 (K(i) = 24 nM), compared to 16N-Pcp27 (K(i) = 1 microM). In addition, virtual alanine scanning of H3 and 16N identified the residues contributing most to binding affinity. Both peptides did not inhibit human cathepsins B and L. In conclusion, these data support the notion that the positively charged H3 helix favors binding, without modifying the selectivity of Pcp27 for congopain.
authors.affiliation: INSERM, U618, Tours F-37000, France, Université François Rabelais, Tours F-37000, France, IFR 135, Tours F-37000, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Godat
authors.forename: Shafinaz
authors.initials: S
authors.lastname: Chowdhury
authors.forename: Fabien
authors.initials: F
authors.lastname: Lecaille
authors.forename: Maya
authors.initials: M
authors.lastname: Belghazi
authors.forename: Enrico O
authors.initials: EO
authors.lastname: Purisima
authors.forename: Gilles
authors.initials: G
authors.lastname: Lalmanach
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051943:Antennapedia Homeodomain Protein / Q000037:antagonists & inhibitors* / Q000737:chemistry; D001665:Binding Sites; D002352:Carrier Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D056668:Cathepsin L; D002403:Cathepsins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D057846:Cell-Penetrating Peptides; D003198:Computer Simulation; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D011485:Protein Binding; D011498:Protein Precursors / Q000737:chemistry*; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry*; D040681:Structural Homology, Protein
chemical_list: D051943:Antennapedia Homeodomain Protein; D002352:Carrier Proteins; D057846:Cell-Penetrating Peptides; D015853:Cysteine Proteinase Inhibitors; D010446:Peptide Fragments; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; C414409:penetratin; D002403:Cathepsins; D003546:Cysteine Endopeptidases; C084086:congopain; C534281:CTSL protein, human; D056668:Cathepsin L