On the Natural History of Flavin-Based Electron Bifurcation

Frontiers in Microbiology

Marianne Guiral¹  Myriam Brugna¹  Simon Duval¹  Carole Baffert¹  Wolfgang Nitschke¹  Barbara Schoepp-Cothenet¹  Frauke Baymann¹  Michael J. Russell² 

[1] CNRS, BIP, UMR 7281, IMM FR3479, Aix-Marseille University, Marseille, France;Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States;

关键词: electron bifurcation;    redox cooperativity;    flavoenzymes;    emergence of life;    redox enzyme construction kit;    bioenergetics;   

DOI  :  10.3389/fmicb.2018.01357

来源: DOAJ

【 摘 要 】

Electron bifurcation is here described as a special case of the continuum of electron transfer reactions accessible to two-electron redox compounds with redox cooperativity. We argue that electron bifurcation is foremost an electrochemical phenomenon based on (a) strongly inverted redox potentials of the individual redox transitions, (b) a high endergonicity of the first redox transition, and (c) an escapement-type mechanism rendering completion of the first electron transfer contingent on occurrence of the second one. This mechanism is proposed to govern both the traditional quinone-based and the newly discovered flavin-based versions of electron bifurcation. Conserved and variable aspects of the spatial arrangement of electron transfer partners in flavoenzymes are assayed by comparing the presently available 3D structures. A wide sample of flavoenzymes is analyzed with respect to conserved structural modules and three major structural groups are identified which serve as basic frames for the evolutionary construction of a plethora of flavin-containing redox enzymes. We argue that flavin-based and other types of electron bifurcation are of primordial importance to free energy conversion, the quintessential foundation of life, and discuss a plausible evolutionary ancestry of the mechanism.

【 授权许可】

Unknown