Rapid Electron Transfer within the III-IV Supercomplex in Corynebacterium glutamicum
Number of Authors: 8
2016 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, 34098Article in journal (Refereed) Published
Complex III in C. glutamicum has an unusual di-heme cyt.c(1) and it co-purifies with complex IV in a supercomplex. Here, we investigated the kinetics of electron transfer within this supercomplex and in the cyt.aa(3) alone (cyt.bc(1) was removed genetically). In the reaction of the reduced cyt.aa(3) with O-2, 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. bc(1)-cyt.aa(3) 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/O-2 reduction activity (similar to 210 e(-)/s). Furthermore, electron transfer from externally added cyt.c to cyt.aa(3) was significantly faster upon removal of cyt.bc(1) from the supercomplex, suggesting that one of the c-hemes occupies a position near Cu-A. 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.c(1) and heme a to the heme a(3)-Cu-B catalytic site of cyt.aa(3).
Place, publisher, year, edition, pages
2016. Vol. 6, 34098
Biological Sciences Chemical Sciences
IdentifiersURN: urn:nbn:se:su:diva-135246DOI: 10.1038/srep34098ISI: 000384175800001OAI: oai:DiVA.org:su-135246DiVA: diva2:1045054