Post doc opportunity – Novel Electron Bifurcating Enzymes (funded by DOE) – University of Georgia

Microorganisms utilize electron bifurcating enzymes to carry out thermodynamically unfavorable

reactions where a single enzyme reversibly couples an endergonic reaction to an exergonic

reaction to generate a net reversible reaction with minimal free energy change. In essence, an

exergonic chemical reaction is used to drive an endergonic one. Electron bifurcation is now

recognized as a major energy coupling system in biology although only a limited number of

examples are known. We very recently discovered a large and diverse family of bifurcating

enzymes, termed Bfu, that is surprisingly ubiquitous in the microbial world. Although very few

Bfu enzymes have been characterized, they are predicted to catalyze reactions involving an

extensive range of substrates not previously known to be involved in electron bifurcation

reactions. Our overriding hypotheses are that 1) Bfu enzymes employ a new bifurcation

mechanism that uses a combination of flavin and iron sulfur clusters, 2) the mechanism and

associated electron transfer pathways allow tremendous flexibility in terms of the range of

substrates that can be used by Bfu members, and 3) numerous types of Bfu enzyme exist that

have yet to be characterized, including membrane-bound ion-translocating complexes, and some

others appear to couple electron bifurcation to non-redox cellular processes.

The specific aims of the proposed research are 1) to determine the unique properties of the

bifurcating site in Bfu enzymes and elucidate the mechanism of electron bifurcation, 2) to

characterize new and unprecedented types of bifurcating Bfu enzymes including those that

potentially utilize substrates such as hydrogen peroxide and acetylene, and ones involved with

cellular processes, such as proteolysis, and 3) to characterize a membrane-bound iontranslocating

Bfu family member that is proposed to couple electron bifurcation to the formation

of chemical gradients. Our objectives will be achieved by utilizing fermentations of

hyperthermophilic and thermophilic microbes, recombinant production and anaerobic purification

of cytoplasmic and membrane enzyme complexes, various biochemical and kinetic techniques,

and UV/visible and EPR spectroscopy. This project will also leverage an on-going collaboration

using cryo-EM to determine structures of electron bifurcating enzymes.

Interested?  Email Mike Adams (, University of Georgia