Human cathepsin V functional expression, tissue distribution, electrostatic surface potential, enzymatic characterization, and chromosomal localization.
Cathepsin V, a thymus and testis-specific human cysteine protease, was expressed in Pichia pastoris, and its physicokinetic properties were determined. Recombinant procathepsin V is autocatalytically activated at acidic pH and is effectively inhibited by various cysteine protease class-specific inhibitors. The S2P2 subsite specificity of cathepsin V was found to be intermediate between those of cathepsins S and L. The substrate binding pocket, S2, accepted both aromatic and nonaromatic hydrophobic residues, whereas cathepsins L and S preferred either an aromatic or nonaromatic hydrophobic residue, respectively. In contrast to cathepsin L, but similar to cathepsin S, cathepsin V exhibited only a very weak collagenolytic activity. Furthermore, cathepsin V was determined to be significantly more stable at mildly acidic and neutral pH than cathepsin L, but distinctly less stable than cathepsin S. A homology structure model of cathepsin V revealed completely different electrostatic potentials on the molecular surface when compared with human cathepsin L. The model-based electrostatic potential of human cathepsin V was neutral to weakly positive at and in the vicinity of the active site cleft, whereas that of cathepsin L was negative over extended regions of the surface. Surprisingly, the electrostatic potential of the human cathepsin V model structure resembled that of the model structure of mouse cathepsin L. These differences in the electrostatic potential at the molecular surfaces provide a reactivity determinant that may be the source of differences in substrate selectivity and pH stability. Cathepsin V was mapped to the chromosomal region 9q22.2, a site adjacent to the cathepsin L locus. The high sequence identity and the overlapping chromosomal gene loci suggest that both proteases evolved from an ancestral cathepsin L-like precursor by gene duplication.
Department of Human Genetics, Mount Sinai School of Medicine, CUNY, New York 10029, USA. brommd01@doc.mssm.edu
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Brömme
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Li
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Barnes
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Mehler
D000595:Amino Acid Sequence; D000818:Animals; D056668:Cathepsin L; D002403:Cathepsins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002899:Chromosomes, Human, Pair 9; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000302:isolation & purification; D010450:Endopeptidases; D004789:Enzyme Activation / Q000235:genetics; D006801:Humans; D007700:Kinetics; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D010843:Pichia / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D055672:Static Electricity
D018076:DNA, Complementary; D012333:RNA, Messenger; D011994:Recombinant Proteins; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L; C534278:Ctsl protein, mouse; C117627:CTSV protein, human