Rapid Electron Transfer within the III-IV Supercomplex in Corynebacterium glutamicum

Graf, Simone Sandra; Fedotovskaya, Olga; Kao, Wei-Chun; Hunte, Carola; Ädelroth, Pia; Bott, Michael; von Ballmoos, Christoph; Brzezinski, Peter (2016). Rapid Electron Transfer within the III-IV Supercomplex in Corynebacterium glutamicum. Scientific Reports, 6(1) Nature Publishing Group 10.1038/srep34098

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Complex III in C. glutamicum has an unusual di-heme cyt. c1 and it co-purifies with complex IV in a supercomplex. Here, we investigated the kinetics of electron transfer within the supercomplex and in the cyt. aa3 alone (cyt. bc1 was removed genetically). In the reaction of the reduced cyt. aa3 with O2, we identified the same sequence of events as with other A-type oxidases. However, even though this reaction is associated with proton uptake, no pH dependence was observed in the kinetics. For the cyt. bc1-cyt. aa3 supercomplex, we observed that electrons from the c-hemes were transferred to CuA with time constants 0.1-1 ms. The b-hemes were oxidized with a time constant of 6.5 ms, indicating that this electron transfer is rate-limiting for the overall quinol oxidation/O2 reduction activity (~210 e-/s). Furthermore, electron transfer from externally added cyt. c to cyt. aa3 was significantly faster upon removal of cyt. bc1 from the supercomplex, suggesting that one of the c-hemes occupies a position near CuA. In conclusion, isolation of the III-IV-supercomplex allowed us to investigate the kinetics of electron transfer from the b hemes, via the di-heme cyt. c1 and heme a to the heme a3-CuB catalytic site of cyt. aa3.

Item Type:

Journal Article (Original Article)


Graf, Simone Sandra


08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)

Graduate School:

Graduate School for Cellular and Biomedical Sciences (GCB)

UniBE Contributor:

Graf, Simone Sandra, von Ballmoos, Christoph


500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry




Nature Publishing Group




Simone Graf

Date Deposited:

27 Jul 2017 08:35

Last Modified:

05 Dec 2022 15:06

Publisher DOI:






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