The parsley plastocyanin-turnip cytochrome f complex: a structurally distorted but kinetically functional acidic patch.
In general, inter-protein electron transfer proceeds via the formation of transient complexes. The initial stage of the interaction between plastocyanin (PCu) and cytochrome f (cyt f ) from plants is mediated by complementary electrostatics. Given the diffuse nature of its acidic patch, parsley PCu is an atypical example of a plant PCu. The interaction of this PCu with turnip cyt f was investigated by stopped-flow kinetics, NMR spectroscopy and protein-docking simulations. We show that, despite the altered acidic patch, parsley PCu is as efficient as spinach PCu in accepting electrons from cyt f, over the physiological range of ionic strength. At high ionic strength, the rate constant for the reaction of cyt f with parsley PCu is twice that of the spinach protein. This difference in reactivity is attributed to variations in the hydrophobic patch of parsley PCu. The results of NMR studies and protein-docking simulations indicate that parsley PCu and its spinach analogue adopt different orientations in their complexes with cyt f.
Crowley
Peter B
PB
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. Da República, Apartado 127, 2781 901 Oeiras, Portugal.
Hunter
David M
DM
Sato
Katsuko
K
McFarlane
William
W
Dennison
Christopher
C
D000595:Amino Acid Sequence; D024342:Amino Acids, Acidic / Q000737:chemistry; D029688:Brassica napus / Q000737:chemistry*; D045348:Cytochromes f / Q000737:chemistry* / Q000378:metabolism*; D004579:Electron Transport; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D028528:Petroselinum / Q000737:chemistry*; D010970:Plastocyanin / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment; D018724:Spinacia oleracea / Q000737:chemistry
D024342:Amino Acids, Acidic; D046911:Macromolecular Substances; D010970:Plastocyanin; D045348:Cytochromes f