Electron transfer between the QmoABC membrane complex and adenosine 5'-phosphosulfate reductase

Area of Science:

• Biochemistry
• Microbiology
• Electrochemistry

Background:

• The dissimilatory adenosine 5 -phosphosulfate reductase (AprAB) is crucial for sulfate reduction.
• The QmoABC membrane complex is the proposed electron donor for AprAB.
• Direct electron transfer between QmoABC and AprAB has not been previously demonstrated.

Purpose of the Study:

• To demonstrate direct electron transfer between the QmoABC complex and AprAB.
• To elucidate the role of QmoABC in delivering electrons to AprAB for sulfate reduction.

Main Methods:

• Cyclic voltammetry using a QmoABC-modified electrode with AprAB.
• Catalytic experiments with immobilized QmoABC, AprAB, and adenosine 5 -phosphosulfate (APS).
• Substrate dependence studies with varying electrode preparations.

Main Results:

• Direct electron transfer between Desulfovibrio desulfuricans QmoABC and AprAB was observed.
• AprAB's FAD redox behavior was identified through electrochemical signatures.
• Catalytic current, dependent on QmoABC, indicated efficient electron delivery for APS reduction.

Conclusions:

• The QmoABC complex directly transfers electrons to AprAB.
• QmoABC is essential for sustaining catalysis in the sulfate reduction pathway.
• This study confirms the role of QmoABC in electron transfer to AprAB.