Evidence for furin-type activity-mediated C-terminal processing of profibrillin-1 and interference in the processing by certain mutations.
Fibrillin-1 is a major component of the 10 nm microfibrils of the extracellular matrix (ECM). It is synthesized as an approximately 350 kDa precursor molecule, profibrillin-1, which is proteolytically processed into its biologically active approximately 320 kDa form. Furin, a calcium-dependent endoprotease of the subtilisin family, which is known to be the processing enzyme for a variety of proproteins, is believed to be responsible for the N-terminal proteolytic cleavage of profibrillin-1. In this article we provide several lines of evidence that the C-terminal trimming of profibrillin-1 also occurs via a furin-type activity. Edman degradation of a small recombinant C-terminal subdomain of fibrillin-1 revealed complete processing of the peptide immediately after the tribasic recognition sequence (R-X-K/R-R) for furin. In vitro expression experiments using another recombinant construct consisting of the C-terminal half of fibrillin-1 indicated that disruption of the putative recognition sequence for furin by site-directed mutagenesis drastically impairs proteolytic processing of the propeptide. In addition, our results suggest that the N-terminal half of fibrillin-1 is necessary for its incorporation into the ECM.
Lönnqvist
L
L
Department of Human Molecular Genetics, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland.
Reinhardt
D
D
Sakai
L
L
Peltonen
L
L
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D000071838:Fibrillin-1; D000071837:Fibrillins; D045683:Furin; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013381:Subtilisins / Q000378:metabolism*; D054392:Adipokines
D000071838:Fibrillin-1; D000071837:Fibrillins; D045683:Furin; D008840:Microfilament Proteins; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D013381:Subtilisins; C000605722:FBN1 protein, human; D054392:Adipokines