Structure of an Electron Transfer Complex: Methylamine Dehydrogenase, Amicyanin, and Cytochrome c _551i

Abstract

The crystal structure of a ternary protein complex has been determined at 2.4 angstrom resolution. The complex is composed of three electron transfer proteins from Paracoccus denitrificans, the quinoprotein methylamine dehydrogenase, the blue copper protein amicyanin, and the cytochrome c551i. The central region of the c551i is folded similarly to several small bacterial c-type cytochromes; there is a 45-residue extension at the amino terminus and a 25-residue extension at the carboxyl terminus. The methylamine dehydrogenase-amicyanin interface is largely hydrophobic, whereas the amicyanin-cytochrome interface is more polar, with several charged groups present on each surface. Analysis of the simplest electron transfer pathways between the redox partners points out the importance of other factors such as energetics in determining the electron transfer rates.

Extensive Domain Motion and Electron Transfer in the Human Electron Transferring Flavoprotein·Medium Chain Acyl-CoA Dehydrogenase Complex

“…the electrostatically guided collision of two essentially rigid bodies for interprotein electron transfer involving small proteins such as cytochrome c (37,38). Crystal structures of ETF complexes now reveal a very different and dynamic interface whereby extensive protein motion is required for effective interprotein electron transfer.…”

Electron Transfer and Conformational Change in Complexes of Trimethylamine Dehydrogenase and Electron Transferring Flavoprotein

“…2B). Dynamic deactivation of excited FAD by the adenosine moiety is well known for FAD in aqueous solution (32). However, the crystal structures of human (24) and Paracoccus denitrificans (33) ETF, and the model of M. methylotrophus ETF (25), indicate the adenosine moiety does not contact the isoalloxazine ring in ETF-bound FAD.…”

Crystal Structure Determinations of Oxidized and Reduced Pseudoazurins from Achromobacter cycloclastes

“…While in methylotrophs pseudoazurins were produced as electron transfer substituted to another blue copper protein named amicyanin at high copper concentration. The ternary complex among methylamine dehydrogenase, amicyanin, and cytochrome c 551 shows that amicyanin accepts an electron from methylamine dehydrogenase (1). On the other hand, in denitrifying bacteria pseudoazurins donate an electron for the reduction of NO 2 Ϫ to NO by nitrite reductase under anaerobic conditions (2)(3)(4)(5).…”