A Study of the Influence of Charged Residues on β-Hairpin Formation by Nuclear Magnetic Resonance and Molecular DynamicsReportar como inadecuado




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The Protein Journal

, Volume 33, Issue 6, pp 525–535

First Online: 15 October 2014

Abstract

Chain reversals are often nucleation sites in protein folding. The β-hairpins of FBP28 WW domain and IgG are stable and have been proved to initiate the folding and are, therefore, suitable for studying the influence of charged residues on β-hairpin conformation. In this paper, we carried out NMR examination of the conformations in solution of two fragments from the FPB28 protein PDB code: 1E0L N-terminal part namely KTADGKT-NH2 1E0L 12–18, D7 and YKTADGKTY-NH2 1E0L 11–19, D9, one from the B3 domain of the protein G PDB code: 1IGD, namely DDATKT-NH2 1IGD 51–56 Dag1, and three variants of Dag1 peptide: DVATKT-NH2 Dag2, OVATKT-NH2 Dag3 and KVATKT-NH2 Dag4, respectively, in which the original charged residue were replaced with non-polar residues or modified charged residues. It was found that both the D7 and D9 peptides form a large fraction bent conformations. However, no hydrophobic contacts between the terminal Tyr residues of D9 occur, which suggests that the presence of a pair of like-charged residues stabilizes chain reversal. Conversely, only the Dag1 and Dag2 peptides exhibit some chain reversal; replacing the second aspartic-acid residue with a valine and the first one with a basic residue results in a nearly extended conformation. These results suggest that basic residues farther away in sequence can result in stabilization of chain reversal owing to screening of the non-polar core. Conversely, smaller distance in sequence prohibits this screening, while the presence oppositely-charged residues can stabilize a turn because of salt-bridge formation.

KeywordsPeptide conformations β-Hairpin Protein G FBP28 protein fragments NMR AbbreviationsFBP28 proteinFormin binding protein

CDCircular dichroism

DSCDifferential scanning calorimetry

NMRNuclear magnetic resonance

TOCSYTwo-dimensional nuclear magnetic resonance spectroscopy

ROESYRotating frame nuclear Overhauser effect spectroscopy

DQF-COSYDouble quantum filtered correlation spectroscopy

TmMelting temperature

Electronic supplementary materialThe online version of this article doi:10.1007-s10930-014-9585-7 contains supplementary material, which is available to authorized users.

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Autor: Joanna Makowska - Wioletta Żmudzińska - Dorota Uber - Lech Chmurzyński

Fuente: https://link.springer.com/







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