Transthyretin is a metallopeptidase with an inducible active site

Transthyretin is a metallopeptidase with an inducible active site

Author Liz, Marcia A. Google Scholar
Leite, Sergio C. Google Scholar
Juliano, Luiz Autor UNIFESP Google Scholar
Saraiva, Maria J. Google Scholar
Damas, Ana M. Google Scholar
Bur, Daniel Google Scholar
Sousa, Monica M. Google Scholar
Institution IBMC
Universidade Federal de São Paulo (UNIFESP)
Univ Porto
Actel Pharmaceut Ltd
Abstract TTR (transthyretin) was found recently to possess proteolytic competency besides its well-known transport capabilities. It was described as a cryptic serine peptidase cleaving multiple natural substrates (including beta-amyloid and apolipoprotein A-I) involved in diseases such as Alzheimer's disease and atherosclerosis. in the present study, we aimed to elucidate the catalytic machinery of TTR. All attempts to identify a catalytic serine residue were unsuccessful. However, metal chelators abolished TTR activity. Proteolytic inhibition by EDTA or 1,10-phenanthroline could be reversed with Zn2+ and Mn2+. These observations, supported by analysis of three-dimensional structures of TTR complexed with Zn2+, led to the hypothesis that TTR is a metallopeptidase. Site-directed mutagenesis of selected amino acids unambiguously confirmed this hypothesis. the TTR active site is inducible and constituted via a protein rearrangement resulting in similar to 7% of proteolytically active TTR at pH 7.4. the side chain of His(88) is shifted near His(90) and Gin(92) establishing a Zn2+-chelating pattern HXHXE not found previously in any metallopeptidase and only conserved in TTR of humans and some other primates. Point mutations of these three residues yielded proteins devoid of proteolytic activity. Glu(72) was identified as the general base involved in activation of the catalytic water. Our results unveil TTR as a metallopeptidase and define its catalytic machinery.
Keywords apolipoprotein A-I
amyloid-beta peptide
Language English
Sponsor Fundacao para a Ciencia e Tecnologia (FCT)
Association Francaise contre les Myopathies, France
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Grant number Fundacao para a Ciencia e Tecnologia (FCT): PTDC/SAU-GMG/111761/2009
Fundacao para a Ciencia e Tecnologia (FCT): PTDC/SAU-ORG/118863/2010
Fundacao para a Ciencia e Tecnologia (FCT): SFRH/BPD/34811/2007
Fundacao para a Ciencia e Tecnologia (FCT): SFRH/BD/72240/2010
Date 2012-05-01
Published in Biochemical Journal. London: Portland Press Ltd, v. 443, p. 769-778, 2012.
ISSN 0264-6021 (Sherpa/Romeo, impact factor)
Publisher Portland Press Ltd
Extent 769-778
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000303944200019

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