The importance of a gatekeeper residue on the aggregation of transthyretin
Sant'Anna, Ricardo (Instituto de Bioquímica Médica Leopoldo de Meis)
Braga, Carolina (Instituto de Bioquímica Médica Leopoldo de Meis)
Varejão, Nathalia (Instituto de Bioquímica Médica Leopoldo de Meis)
Pimenta, Karinne M. (Instituto de Bioquímica Médica Leopoldo de Meis)
Graña Montes, Ricardo (Universitat Autònoma de Barcelona. Institut de Biotecnologia i de Biomedicina "Vicent Villar Palasí")
Alves, Aline (Instituto de Bioquímica Médica Leopoldo de Meis)
Cortines, Juliana (Instituto de Microbiologia Professor Paulo de Goés)
Cordeiro, Yraima (Universidade Federal do Rio de Janeiro. Faculdade de Farmácia)
Ventura, Salvador (Universitat Autònoma de Barcelona. Institut de Biotecnologia i de Biomedicina "Vicent Villar Palasí")
Foguel, Debora (From the Instituto de Bioquímica Médica Leopoldo de Meis, Programa de Biologia Estrutural)

Data:	2014
Resum:	Background: Proteins have adopted negative design to diminish aggregation. Results: The replacement of Lys-35 by Leu increases the amyloidogenicity of the 26-57 segment of TTR as well as the entire protein. Conclusion: Lys-35 is as a gatekeeper residue in TTR, and its protective effect is suppressed by heparin. Significance: The elucidation of the principles that govern protein aggregation is helpful for the design of strategies against amyloid diseases. Protein aggregation into β-sheet-enriched amyloid fibrils is associated with an increasing number of human disorders. The adoption of such amyloid conformations seems to constitute a generic property of polypeptide chains. Therefore, during evolution, proteins have adopted negative design strategies to diminish their intrinsic propensity to aggregate, including enrichment of gatekeeper charged residues at the flanks of hydrophobic aggregation-prone segments. Wild type transthyretin (TTR) is responsible for senile systemic amyloidosis, and more than 100 mutations in the TTR gene are involved in familial amyloid polyneuropathy. The TTR 26-57 segment bears many of these aggressive amyloidogenic mutations as well as the binding site for heparin. We demonstrate here that Lys-35 acts as a gatekeeper residue in TTR, strongly decreasing its amyloidogenic potential. This protective effect is sequence-specific because Lys-48 does not affect TTR aggregation. Lys-35 is part of the TTR basic heparin-binding motif. This glycosaminoglycan blocks the protective effect of Lys-35, probably by neutralization of its side chain positive charge. A K35L mutation emulates this effect and results in the rapid self-assembly of the TTR 26-57 region into amyloid fibrils. This mutation does not affect the tetrameric protein stability, but it strongly increases its aggregation propensity. Overall, we illustrate how TTR is yet another amyloidogenic protein exploiting negative design to prevent its massive aggregation, and we show how blockage of conserved protective features by endogenous factors or mutations might result in increased disease susceptibility.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Amyloid ; Heparin ; Peptides ; Protein Aggregation ; Protein Misfolding ; Aggregation Propensity ; Gatekeeper Residue ; Rational Mutation ; Transthyretin
Publicat a:	Journal of biological chemistry, Vol. 289, no. 41 (Oct. 2014) , p. 28324-28337, ISSN 1083-351X

DOI: 10.1074/jbc.M114.563981
PMID: 25086037

14 p, 3.1 MB

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