Evidence for Furin-type Activity-Mediated C-terminal Processing of Profibrillin-1 and Interference in the Processing by Certain Mutations

• Published in: Human molecular genetics 1998-12, Vol.7 (13), p.2039-2044
• Main Authors: Lönnqvist, L., Reinhardt, D., Sakai, L., Peltonen, L.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Biological and medical sciences; COS Cells; Fibrillin-1; Fibrillins; Fundamental and applied biological sciences. Psychology; Furin; Genes. Genome; Microfilament Proteins - chemistry; Microfilament Proteins - genetics; Microfilament Proteins - metabolism; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation; Protein Precursors - chemistry; Protein Precursors - genetics; Protein Precursors - metabolism; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Subtilisins - metabolism
• ISSN: 0964-6906; 1460-2083; 1460-2083
• DOI: 10.1093/hmg/7.13.2039

Fibrillin-1 is a major component of the 10 nm microfibrils of the extracellular matrix (ECM). It is synthesized as an ∼350 kDa precursor molecule, profibrillin-1, which is proteolytically processed into its biologically active ∼320 kDa form. Furin, a calcium-dependent endoprotease of the subtilisin family, which is known to be the processing enzyme for a variety of pro-proteins, 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.