bims-resufa Biomed News
on Respiratory supercomplex factors
Issue of 2023‒12‒03
two papers selected by
Gavin McStay, Liverpool John Moores University



  1. J Biochem. 2023 Nov 28. pii: mvad100. [Epub ahead of print]
      With population aging, cognitive impairments and movement disorders due to neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and dementia with Lewy bodies (DLB), are increasingly considered as key social issues. Clinically, it has remained challenging to diagnose them before the onset of symptoms because of difficulty to observe the progressive loss of neurons in the brain. Therefore, with exploratory research into biomarkers, a number of candidates have previously been proposed, such as activities of mitochondrial respiratory chain complexes in blood in AD and PD. In this study, we focused on the formation of mitochondrial respiratory chain supercomplexes (SCs) because the formation of SC itself modulates the activity of each complex. Here we investigated the SC formation in leukocytes from patients with AD, PD, and DLB. Our results showed that SCs were well formed in AD and PD compared with controls, while poorly formed in DLB. We highlighted that the disruption of the SC formation correlated with the progression of PD and DLB. Taking our findings together, we propose that pronounced SC formation would already have occurred before the onset of AD, PD, and DLB and, with the progression of neurodegeneration, the SC formation would gradually be disrupted.
    Keywords:  Alzheimer’s disease; Parkinson’s disease; dementia with Lewy bodies; high-resolution clear native polyacrylamide gel electrophoresis; in-gel activity assay; mitochondrial respiratory chain complexes
    DOI:  https://doi.org/10.1093/jb/mvad100
  2. Mitochondrion. 2023 Nov 29. pii: S1567-7249(23)00093-4. [Epub ahead of print]
      Over the past decades, models of the organization of mitochondrial respiratory system have been controversial. The goal of this perspective is to assess this "conflict of models" by focusing on specific kinetic evidence in the two distinct segments of Coenzyme Q- and Cytochrome c-mediated electron transfer. Respiratory supercomplexes provide kinetic advantage by allowing a restricted diffusion of Coenzyme Q and Cytochrome c, and short-range interaction with their partner enzymes. In particular, electron transfer from NADH is compartmentalized by channeling of Coenzyme Q within supercomplexes, whereas succinate oxidation proceeds separately using the free Coenzyme Q pool. Previous evidence favoring Coenzyme Q random diffusion in the NADH-dependent electron transfer is due to downstream flux interference and misinterpretation of results. Indeed, electron transfer by complexes III and IV via Cytochrome c is less strictly dependent on substrate channeling in mammalian mitochondria. We briefly describe these differences and their physiological implications.
    Keywords:  Coenzyme Q or ubiquinone; Cytochrome c; channeling; diffusion; respiratory supercomplex
    DOI:  https://doi.org/10.1016/j.mito.2023.11.005