Crystal structures of native and inhibited forms of human cathepsin D: implications for lysosomal targeting and drug design.
Cathepsin D (EC 3.4.23.5) is a lysosomal protease suspected to play important roles in protein catabolism, antigen processing, degenerative diseases, and breast cancer progression. Determination of the crystal structures of cathepsin D and a complex with pepstatin at 2.5 A resolution provides insights into inhibitor binding and lysosomal targeting for this two-chain, N-glycosylated aspartic protease. Comparison with the structures of a complex of pepstatin bound to rhizopuspepsin and with a human renin-inhibitor complex revealed differences in subsite structures and inhibitor-enzyme interactions that are consistent with affinity differences and structure-activity relationships and suggest strategies for fine-tuning the specificity of cathepsin D inhibitors. Mutagenesis studies have identified a phosphotransferase recognition region that is required for oligosaccharide phosphorylation but is 32 A distant from the N-domain glycosylation site at Asn-70. Electron density for the crystal structure of cathepsin D indicated the presence of an N-linked oligosaccharide that extends from Asn-70 toward Lys-203, which is a key component of the phosphotransferase recognition region, and thus provides a structural explanation for how the phosphotransferase can recognize apparently distant sites on the protein surface.
Structural Biochemistry Program, Program Resources Inc./DynCorp, National Cancer Institute-Frederick Cancer Research and Development Center, MD 21702.
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Baldwin
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Bhat
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Gulnik
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Hosur
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Cachau
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Collins
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Silva
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Erickson
D000595:Amino Acid Sequence; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry; D001692:Biological Transport; D002402:Cathepsin D / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D015195:Drug Design; D006031:Glycosylation; D006801:Humans; D008247:Lysosomes; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010436:Pepstatins / Q000737:chemistry*; D010770:Phosphotransferases; D011487:Protein Conformation; D012083:Renin / Q000737:chemistry; D014961:X-Ray Diffraction
D010436:Pepstatins; C014195:Streptomyces pepsin inhibitor; D010770:Phosphotransferases; D016282:Aspartic Acid Endopeptidases; D012083:Renin; C035794:rhizopuspepsin; D002402:Cathepsin D; C031375:pepstatin