Protein GB1 folding and assembly from structural elements.

Bauer, Mikael C. and Xue, Wei-Feng and Linse, Sara (2009) Protein GB1 folding and assembly from structural elements. International Journal of Molecular Sciences, 10 (4). pp. 1552-1566. ISSN 1422-0067. (doi:https://doi.org/10.3390/ijms10041552) (Full text available)

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http://dx.doi.org/10.3390/ijms10041552

Abstract

Folding of the Protein G B1 domain (PGB1) shifts with increasing salt concentration from a cooperative assembly of inherently unstructured subdomains to an assembly of partly pre-folded structures. The salt-dependence of pre-folding contributes to the stability minimum observed at physiological salt conditions. Our conclusions are based on a study in which the reconstitution of PGB1 from two fragments was studied as a function of salt concentrations and temperature using circular dichroism spectroscopy. Salt was found to induce an increase in beta-hairpin structure for the C-terminal fragment (residues 41 - 56), whereas no major salt effect on structure was observed for the isolated N-terminal fragment (residues 1 - 41). In line with the increasing evidence on the interrelation between fragment complementation and stability of the corresponding intact protein, we also find that salt effects on reconstitution can be predicted from salt dependence of the stability of the intact protein. Our data show that our variant (which has the mutations T2Q, N8D, N37D and reconstitutes in a manner similar to the wild type) displays the lowest equilibrium association constant around physiological salt concentration, with higher affinity observed both at lower and higher salt concentration. This corroborates the salt effects on the stability towards denaturation of the intact protein, for which the stability at physiological salt is lower compared to both lower and higher salt concentrations. Hence we conclude that reconstitution reports on molecular factors that govern the native states of proteins.

Item Type: Article
Subjects: Q Science
Q Science > QC Physics
Q Science > QD Chemistry
Q Science > QP Physiology (Living systems) > QP517 Biochemistry
Divisions: Faculties > Sciences > School of Biosciences
Depositing User: Wei-Feng Xue
Date Deposited: 11 Jun 2013 13:28 UTC
Last Modified: 17 Jan 2017 10:16 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/34258 (The current URI for this page, for reference purposes)
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