W-F Substitutions in Apomyoglobin Increase the Local Flexibility of the N-terminal Region Causing Amyloid Aggregation: A H/D Exchange Study

Author(s): Giuseppe Infusini, Clara Iannuzzi, Silvia Vilasi, Rosa Maritato, Leila Birolo, Daniela Pagnozzi, Piero Pucci, Gaetano Irace, Ivana Sirangelo.

Journal Name: Protein & Peptide Letters

Volume 20 , Issue 8 , 2013

Submit Manuscript
Submit Proposal

Abstract:

Myoglobin is an α-helical globular protein containing two highly conserved tryptophanyl residues at positions 7 and 14 in the N-terminal region. The simultaneous substitution of the two residues impairs the productive folding of the protein making the polypeptide chain highly prone to aggregate forming amyloid fibrils at physiological pH and room temperature. The role played by tryptophanyl residues in driving the productive folding process was investigated by providing structural details at low resolution of compact intermediate of three mutated apomyoglobins, i.e., W7F, W14F and the amyloid forming mutant W7FW14F.

In particular, we followed the hydrogen/deuterium exchange rate of protein segments using proteolysis with pepsin followed by mass spectrometry analysis. The results revealed significant differences in the N-terminal region, consisting in an alteration of the physico-chemical properties of the 7-11 segment for W7F and in an increase of local flexibility of the12-29 segment for W14F. In the double trypthophanyl substituted mutant, these effects are additive and impair the formation of native-like contacts and favour inter-chain interactions leading to protein aggregation and amyloid formation at physiological pH.

Keywords: Amyloid aggregation, apomyoglobin, H/D exchanges, protein folding, protein misfolding, W-F substitution.

Rights & PermissionsPrintExport Cite as


Article Details

VOLUME: 20
ISSUE: 8
Year: 2013
Page: [898 - 904]
Pages: 7
DOI: 10.2174/0929866511320080006

Article Metrics

PDF: 16