Crystal Structure and Autoactivation Pathway of the Precursor Form of Human Tripeptidyl-peptidase 1, the Enzyme Deficient in Late Infantile Ceroid Lipofuscinosis

Late infantile neuronal ceroid lipofuscinosis is a fatal childhood neurological disorder caused by a deficiency in the lysosomal protease tripeptidyl-peptidase 1 (TPP1). TPP1 represents the only known mammalian member of the S53 family of serine proteases, a group characterized by a subtilisin-like...

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Bibliographic Details
Published in:The Journal of biological chemistry 2009-02, Vol.284 (6), p.3985-3997
Main Authors: Guhaniyogi, Jayita, Sohar, Istvan, Das, Kalyan, Stock, Ann M., Lobel, Peter
Format: Article
Language:English
Subjects:
Aminopeptidases
BASIC BIOLOGICAL SCIENCES
Binding Sites - genetics
Cell Line
CRYSTAL STRUCTURE
Crystallography, X-Ray
Dipeptidyl-Peptidases and Tripeptidyl-Peptidases
Endopeptidases - chemistry
Endopeptidases - genetics
Endopeptidases - metabolism
Enzyme Activation - genetics
Enzyme Precursors - chemistry
Enzyme Precursors - genetics
Enzyme Precursors - metabolism
ENZYMES
GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
Glycosylation
HUMAN POPULATIONS
Humans
MATERIALS SCIENCE
Models, Molecular
Mutation
national synchrotron light source
Neuronal Ceroid-Lipofuscinoses - enzymology
Neuronal Ceroid-Lipofuscinoses - genetics
PRECURSOR
Protein Folding
Protein Structure, Secondary - genetics
Protein Structure, Tertiary - genetics
Serine Proteases
Structural Homology, Protein
Structure-Activity Relationship
Tripeptidyl-Peptidase 1
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Description
Summary:Late infantile neuronal ceroid lipofuscinosis is a fatal childhood neurological disorder caused by a deficiency in the lysosomal protease tripeptidyl-peptidase 1 (TPP1). TPP1 represents the only known mammalian member of the S53 family of serine proteases, a group characterized by a subtilisin-like fold, a Ser-Glu-Asp catalytic triad, and an acidic pH optimum. TPP1 is synthesized as an inactive proenzyme (pro-TPP1) that is proteolytically processed into the active enzyme after exposure to low pH in vitro or targeting to the lysosome in vivo. In this study, we describe an endoglycosidase H-deglycosylated form of TPP1 containing four Asn-linked N-acetylglucosamines that is indistinguishable from fully glycosylated TPP1 in terms of autocatalytic processing of the proform and enzymatic properties of the mature protease. The crystal structure of deglycosylated pro-TPP1 was determined at 1.85 Å resolution. A large 151-residue C-shaped prodomain makes extensive contacts as it wraps around the surface of the catalytic domain with the two domains connected by a 24-residue flexible linker that passes through the substrate-binding groove. The proenzyme structure reveals suboptimal catalytic triad geometry with its propiece linker partially blocking the substrate-binding site, which together serve to prevent premature activation of the protease. Finally, we have identified numerous processing intermediates and propose a structural model that explains the pathway for TPP1 activation in vitro. These data provide new insights into TPP1 function and represent a valuable resource for constructing improved TPP1 variants for treatment of late infantile neuronal ceroid lipofuscinosis.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M806943200