Evidence for furin-type activity-mediated C-terminal processing of profibrillin-1 and interference in the processing by certain mutations

Author: Reinhardt D.  

Publisher: Oxford University Press

ISSN: 1460-2083

Source: Human Molecular Genetics, Vol.7, Iss.13, 1998-12, pp. : 2039-2044

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Abstract

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 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.

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