The protonmotive force and respiratory control

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COST Action CA15203 (2016-2021): MitoEAGLE
Evolution-Age-Gender-Lifestyle-Environment: mitochondrial fitness mapping

The protonmotive force and respiratory control

OXPHOS-coupled energy cycles. From Gnaiger 2014 MitoPathways.

» WG1 Action - WG1 MITOEAGLE protocols, terminology, documentation: Standard operating procedures and user requirement document: Protocols, terminology, documentation

» WG1 Project application

Capacities of the electron transfer system, oxidative phosphorylation and resting LEAK respiration (ETS, OXPHOS, LEAK) and four-compartmental OXPHOS model. (i) Capacity of the ETS module, E, in the noncoupled state, generating the protonmotive force, Δp_mt. OXPHOS capacity, P, is partitioned into (ii) the dissipative LEAK component, L (disspation of Δp_mt), and (iii) the free OXPHOS capacity, ≈P=P-L (energy conversion driven by Δp_mt). If ≈P is limited by the capacity of the phosphorylation system, then (iv) the apparent ETS excess capacity, ExP=E-P, is available to drive coupled processes other than phosphorylation without competing with ATP production. Free divided by total ETS capacity, ≈E/E, is the ETS coupling efficiency. Free divided by total OXPHOS capacity, ≈P/P, is the OXPHOS coupling efficiency. From Gnaiger 2014 MitoPathways.

Mitochondrial respiratory coupling control - a conceptual perspective on terminology

Scope of MITOEAGLE publication: Respiratory states

• Target a broad audience – also the new generation
• List of terms including historical terms; abbreviations (mtDNA, mt to abbreviate mitochondr*); OXPHOS capacity versus State 3 (discuss saturating ADP/Pi .. concentrations)
• Scientific terminology should be general and platform independent - demands of the working groups

Structure

1. From bioenergetics to mitochondrial physiology - historical view
2. The mitochondrial respiratory system
3. Rates and states - Units (important for a database); analogous to electic terms: Flow [C.s-1]; Flux [C.s-1.m-2]; Rate (?)
4. Intact cells, mt preparation and normalization
5. Coupling states: mt-preparations and intact cells
6. Pathway states: mt-preparations and intact cells
7. References

Journal

• Int J Biochem Cell Biol (W Koopman will be the new editor); Open Access is a requirement

Action

» Pre-publication: Mitochondrial respiratory control states

» MitoPedia: Respiratory control ratios

» MitoPedia: SUIT

References

• Gnaiger 2014 MitoPathways
• Lemieux H, Blier PU, Gnaiger E (2017) Remodeling pathway control of oxidative phosphorylation by temperature in the heart. bioRxiv doi10.1101/103457. - »Bioblast link«
• Miller 1991 Scientific American Library
• http://www.nature.com/cdd/journal/v16/n1/full/cdd2008150a.html
• http://www.nature.com/cdd/journal/v20/n7/full/cdd201327a.html

Next steps

Mitochondrial respiratory pathway control - substrates and inhibitors

Switch to pathway-related nomenclature instead of enzyme-linked terminology (N/NS/S versus CI/CI+II/CII)