Outer membrane compositions enhance the rate of extracellular electron transport via cell-surface MtrC protein in Shewanella oneidensis MR-1

While cell membrane composition is critical for the function of membrane proteins, membrane modification has not been used to control the rate of extracellular electron transfer (EET) via the outer membrane protein complexes. Here, the rate of electron flow via the cell-surface redox protein, MtrC, was highly enhanced upon change in the outer membrane composition in Shewanella oneidensis MR-1. The MR-1 strain was pre-cultured at 4 degrees C and 30 degrees C to initiate differentiation of membrane composition. The whole-cell difference electrochemical assay of wild-type and mutant strains lacking MtrC suggested that the rate of EET via MtrC increased approximately 18 times at 4 degrees C than 30 degrees C. Circular dichroism spectroscopy showed that the molar exciton coupling coefficient for inter-heme interaction in MtrC increased in MR-1 at 4 degrees C than 30 degrees C. Results suggest that membrane modification may be a novel strategy for improving the efficiency of EET-based technologies.

Automated summary

Alteration of outer membrane composition in Shewanella oneidensis MR-1 significantly enhanced the electron flow rate via cell-surface redox protein MtrC. Culturing at lower temperatures increased the rate of extracellular electron transfer, suggesting that modification of membrane composition may be a novel strategy for improving the efficiency of EET-based technologies.