HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bhattacharjya, S. Articles by Ni, F. Search for Related Content PubMed PubMed Citation Articles by Bhattacharjya, S. Articles by Ni, F. Social Bookmarking                   What's this?

pH-induced conformational transitions of a molten–globule–like state of the inhibitory prodomain of furin: Implications for zymogen activation

¹ Biomolecular Nuclear Magnetic Resonance Laboratory, Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec H4P 2R2, Canada
² Diseases of Aging Unit, Loeb Health Research Institute at the Ottawa Hospital, Ottawa, Ontario ON K1Y 4K9, Canada
³ Biochemical and Molecular Neuroendocrinology Laboratories, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada

Reprint requests to: Dr. Feng Ni, Biomolecular Nuclear Magnetic Resonance Laboratory, Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, Quebec H4P 2R2, Canada; e-mail: feng.ni{at}nrc.ca; fax: (514) 496-5143.

The endoprotease furin, which belongs to the family of mammalian proprotein convertase (PC), is synthesized as a zymogen with an N-terminal, 81-residue inhibitory prodomain. It has been shown that the proenzyme form of furin undergoes a multistep `autocatalytic' removal of the prodomain at the C-terminal side of the two consensus sites, R<sub>78</sub>-T-K-R<sub>81</sub> and R<sub>44</sub>-G-V-T-K-R<sub>49</sub>. The furin-mediated cleavage at R<sub>44</sub>-G-V-T-K-R<sub>49</sub>, in particular, is significantly accelerated in an `acidic' environment. Here, we show that under neutral pH conditions, the inhibitory prodomain of furin is partially folded and undergoes conformational exchanges as indicated by extensive broadening of the NMR spectra. Presence of many ring-current shifted methyl resonances suggests that the partially folded state of the prodomain may still possess a `semirigid' protein core with specific packing interactions among amino acid side chains. Measurements of the hydrodynamic radii and compaction factors indicate that this partially folded state is significantly more compact than a random chain. The conformational stability of the prodomain appears to be pH sensitive, in that the prodomain undergoes an unfolding transition towards acidic conditions. Our NMR analyses establish that the acid-induced unfolding is mainly experienced by the residues from the C-terminal half of the prodomain (residues R₄₄–R₈₁) that contains the two furin cleavage sites. A 38-residue peptide fragment derived from the entire pH-sensitive C-terminal region (residues R₄₄–R₈₁) does not exhibit any exchange-induced line broadening and adopts flexible conformations. We propose that at neutral pH, the cleavage site R₄₄-G-V-T-K-R₄₉ is buried within the protein core that is formed in part by residues from the N-terminal region, and that the cleavage site becomes exposed under acidic conditions, leading to a facile cleavage by the furin enzyme.

Keywords: Prodomain; furin; heteronuclear NMR; protease activation; convertases

Abbreviations: PCs, proprotein convertases • NMR, nuclear magnetic resonance • NOESY, nuclear Overhauser effect spectroscopy • TOCSY, total correlation spectroscopy • HSQC, heteronuclear single quantum coherence

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				S.-N. Lee and I. Lindberg 7B2 Prevents Unfolding and Aggregation of Prohormone Convertase 2 Endocrinology, August 1, 2008; 149(8): 4116 - 4127. [Abstract] [Full Text] [PDF]

				S. F. Feliciangeli, L. Thomas, G. K. Scott, E. Subbian, C.-H. Hung, S. S. Molloy, F. Jean, U. Shinde, and G. Thomas Identification of a pH Sensor in the Furin Propeptide That Regulates Enzyme Activation J. Biol. Chem., June 9, 2006; 281(23): 16108 - 16116. [Abstract] [Full Text] [PDF]

				A. M. Weljie, A. P. Yamniuk, H. Yoshino, Y. Izumi, and H. J. Vogel Protein conformational changes studied by diffusion NMR spectroscopy: Application to helix-loop-helix calcium binding proteins Protein Sci., February 1, 2003; 12(2): 228 - 236. [Abstract] [Full Text] [PDF]

				E. D. Anderson, S. S. Molloy, F. Jean, H. Fei, S. Shimamura, and G. Thomas The Ordered and Compartment-specific Autoproteolytic Removal of the Furin Intramolecular Chaperone Is Required for Enzyme Activation J. Biol. Chem., April 5, 2002; 277(15): 12879 - 12890. [Abstract] [Full Text] [PDF]