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Shifting the Equilibrium between the Encounter State and the Specific Form of a Protein Complex by Interfacial Point Mutations

Volkov, Alexander N and Bashir, Qamar and Worrall, Jonathan AR and Ullmann, G Matthias and Ubbink, Marcellus (2010) 'Shifting the Equilibrium between the Encounter State and the Specific Form of a Protein Complex by Interfacial Point Mutations.' Journal of the American Chemical Society, 132 (33). pp. 11487-11495. ISSN 0002-7863

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Recent experimental studies have confirmed a long-held view that protein complex formation proceeds via a short-lived encounter state. The population of this transient intermediate, stabilized mainly by long-range electrostatic interactions, varies among different complexes. Here we show that the occupancy of the encounter state can be modulated across a broad range by single point mutations of interfacial residues. Using a combination of Monte Carlo simulations and paramagnetic relaxation enhancement NMR spectroscopy, we illustrate that it is possible to both enhance and diminish the binding specificity in an electron transfer complex of yeast cytochrome c (Cc) and cytochrome c peroxidase. The Cc T12A mutation decreases the population of the encounter to 10% as compared with 30% in the wild-type complex. More dramatically, the Cc R13A substitution reverses the relative occupancies of the stereospecific and the encounter forms, with the latter now being the dominant species with the population of 80%. This finding indicates that the encounter state can make a large contribution to the stability of a protein complex. Also, it appears that by adjusting the amount of the encounter through a judicious choice of point mutations, we can remodel the energy landscape of a protein complex and tune its binding specificity. © 2010 American Chemical Society.

Item Type: Article
Uncontrolled Keywords: Saccharomyces cerevisiae; Cytochromes c; Cytochrome-c Peroxidase; Calorimetry; Crystallography, X-Ray; Magnetic Resonance Spectroscopy; Monte Carlo Method; Point Mutation; Models, Molecular
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health
Faculty of Science and Health > Life Sciences, School of
SWORD Depositor: Elements
Depositing User: Elements
Date Deposited: 11 Oct 2011 14:55
Last Modified: 18 Aug 2022 11:33

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