4H0J

Mutant M58C of Nostoc sp Cytochrome c6

Summary for 4H0J

• Entry DOI: 10.2210/pdb4h0j/pdb
• Related: 4GYD 4H0K
• Descriptor: Cytochrome c6, HEME C (3 entities in total)
• Functional Keywords: electron transport, heme binding
• Biological source: Nostoc
• Total number of polymer chains: 6
• Total formula weight: 58403.34

Authors

Pannu, N.S.,Skubak, P.,Ubbink, M.,Cavazzini, D.,Rossi, G.L. (deposition date: 2012-09-08, release date: 2013-09-11, Last modification date: 2024-11-13)

Primary citation

Diaz-Moreno, I.,Hulsker, R.,Skubak, P.,Foerster, J.M.,Cavazzini, D.,Finiguerra, M.G.,Diaz-Quintana, A.,Moreno-Beltran, B.,Rossi, G.L.,Ullmann, G.M.,Pannu, N.S.,De la Rosa, M.A.,Ubbink, M.
The dynamic complex of cytochrome c6 and cytochrome f studied with paramagnetic NMR spectroscopy
Biochim.Biophys.Acta, 1837:1305-1315, 2014

PubMed Abstract: The rapid transfer of electrons in the photosynthetic redox chain is achieved by the formation of short-lived complexes of cytochrome b6f with the electron transfer proteins plastocyanin and cytochrome c6. A balance must exist between fast intermolecular electron transfer and rapid dissociation, which requires the formation of a complex that has limited specificity. The interaction of the soluble fragment of cytochrome f and cytochrome c6 from the cyanobacterium Nostoc sp. PCC 7119 was studied using NMR spectroscopy and X-ray diffraction. The crystal structures of wild type, M58H and M58C cytochrome c6 were determined. The M58C variant is an excellent low potential mimic of the wild type protein and was used in chemical shift perturbation and paramagnetic relaxation NMR experiments to characterize the complex with cytochrome f. The interaction is highly dynamic and can be described as a pure encounter complex, with no dominant stereospecific complex. Ensemble docking calculations and Monte-Carlo simulations suggest a model in which charge-charge interactions pre-orient cytochrome c6 with its haem edge toward cytochrome f to form an ensemble of orientations with extensive contacts between the hydrophobic patches on both cytochromes, bringing the two haem groups sufficiently close to allow for rapid electron transfer. This model of complex formation allows for a gradual increase and decrease of the hydrophobic interactions during association and dissociation, thus avoiding a high transition state barrier that would slow down the dissociation process.

PubMed: 24685428
DOI: 10.1016/j.bbabio.2014.03.009

Experimental method

X-RAY DIFFRACTION (2 Å)