title: Efficient electron transfer in a protein network lacking specific interactions.
abstract: In many biochemical processes, proteins need to bind partners amidst a sea of other molecules. Generally, partner selection is achieved by formation of a single-orientation complex with well-defined, short-range interactions. We describe a protein network that functions effectively in a metabolic electron transfer process but lacks such specific interactions. The soil bacterium Paracoccus denitrificans oxidizes a variety of compounds by channeling electrons into the main respiratory pathway. Upon conversion of methylamine by methylamine dehydrogenase, electrons are transported to the terminal oxidase to reduce molecular oxygen. Steady-state kinetic measurements and NMR experiments demonstrate a remarkable number of possibilities for the electron transfer, involving the cupredoxin amicyanin as well as four c-type cytochromes. The observed interactions appear to be governed exclusively by the electrostatic nature of each of the proteins. It is concluded that Paracoccus provides a pool of cytochromes for efficient electron transfer via weak, ill-defined interactions, in contrast with the view that functional biochemical interactions require well-defined molecular interactions. It is proposed that the lack of requirement for specificity in these interactions might facilitate the integration of new metabolic pathways.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Parma, 43100 Parma, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Meschi
authors.forename: Frank
authors.initials: F
authors.lastname: Wiertz
authors.forename: Linda
authors.initials: L
authors.lastname: Klauss
authors.forename: Anneloes
authors.initials: A
authors.lastname: Blok
authors.forename: Bernd
authors.initials: B
authors.lastname: Ludwig
authors.forename: Angelo
authors.initials: A
authors.lastname: Merli
authors.forename: Hendrik A
authors.initials: HA
authors.lastname: Heering
authors.forename: Gian Luigi
authors.initials: GL
authors.lastname: Rossi
authors.forename: Marcellus
authors.initials: M
authors.lastname: Ubbink
mesh_terms: D055664:Electrochemical Techniques; D004579:Electron Transport; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D010084:Oxidation-Reduction; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry; D010231:Paracoccus denitrificans / Q000737:chemistry; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry*
chemical_list: D011506:Proteins; C021567:methylamine dehydrogenase; D000587:Oxidoreductases Acting on CH-NH Group Donors