A C-terminal domain conserved in precursor processing proteases is required for intramolecular N-terminal maturation of pro-Kex2 protease.
The Kex2 protease of the yeast Saccharomyces cerevisiae is the prototype of a family of eukaryotic subtilisin homologs thought to process prohormones and other precursors in the secretory pathway. Deletion analysis of Kex2 protease shows that a sequence of 154-159 residues carboxyl to the subtilisin domain is essential for the formation of active enzyme. Disruption of this region, termed the 'P-domain', blocks the normally rapid intra-molecular cleavage of the N-terminal pro-segment of pro-Kex2 protease in the endoplasmic reticulum (ER). The C-terminal boundary of the P-domain coincides closely with the endpoint of similarity between Kex2 protease and its mammalian homologues. The conservation of and functional requirement for the P-domain sharpens the distinction between a 'Kex2 family' of processing enzymes and degradative 'subtilases', and implies that the Kex2-related enzymes have in common entirely novel structural features that are important in the maturation of precursor polypeptide substrates. Failure to cleave the N-terminal pro-domain, due either to truncation of the P-domain or to mutation of the active site histidine or serine, results in stable, intracellular retention of pro-enzyme, apparently in the ER. Thus pro-Kex2 protease appears to contain an ER retention signal which is removed or destroyed by cleavage of the pro-domain.
Gluschankof
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Department of Biochemistry, Beckman Center for Molecular and Genetic Medicine, Stanford University School of Medicine, CA 94305-5307.
Fuller
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D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D043484:Proprotein Convertases; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013381:Subtilisins / Q000096:biosynthesis* / Q000235:genetics
D004792:Enzyme Precursors; D005656:Fungal Proteins; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; D043484:Proprotein Convertases; D013381:Subtilisins; C058751:KEX2 protein, S cerevisiae