Biological Sciences Faculty Publications

Title

Plastocyanin-cytochrome F Interactions: The Influence Of Hydrophobic Patch Mutations Studied By Nmr Spectroscopy

Document Type

Article

Abstract

Transient complex formation between plastocyanin from Prochlorothrix hollandica and cytochrome f from Phormidium laminosum was investigated using nuclear magnetic resonance (NMR) spectroscopy. Binding curves derived from NMR titrations at 10 mM ionic strength reveal a 1:1 stoichiometry and a binding constant of 6 ((2) 103 M-1 for complex formation, 1 order of magnitude larger than that for the physiological plastocyanin-cytochrome f complex from Ph. laminosum. Chemicalshift perturbation mapping indicates that the hydrophobic patch of plastocyanin is involved in the complex interface. When the unusual hydrophobic patch residues of P. hollandica plastocyanin were reverted to the conserved residues found in most other plastocyanins (Y12G/P14L), the binding constant for the interaction with cytochrome f was unaffected. However, the chemical shift perturbation map was considerably different, and the size of the average perturbation decreased by 40%. The complexes of both the wild-type and double mutant plastocyanin with cytochrome f were sensitive to ionic strength, contrary to the physiological complex. The possible implications of these findings for the mechanism of transient complex formation are discussed.

Publication Date

12-2002

Publication Title

Biochemistry

Volume

41

Issue

52

Start Page No.

15698

End Page No.

15705

DOI

10.1021/bi026349b

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