Acin-Perez 2008 Mol Cell
|Acín-Pérez R, Fernández-Silva P, Peleato ML, Pérez-Martos A, Enriquez JA (2008) Respiratory active mitochondrial supercomplexes. Mol Cell 32:529-39. doi: 10.1016/j.molcel.2008.10.021.|
» [https://pubmed.ncbi.nlm.nih.gov/19026783/ PMID: 19026783 Open Access
Abstract: The structural organization of the mitochondrial respiratory complexes as four big independently moving entities connected by the mobile carriers CoQ and cytochrome c has been challenged recently. Blue native gel electrophoresis reveals the presence of high-molecular-weight bands containing several respiratory complexes and suggesting an in vivo assembly status of these structures (respirasomes). However, no functional evidence of the activity of supercomplexes as true respirasomes has been provided yet. We have observed that (1) supercomplexes are not formed when one of their component complexes is absent; (2) there is a temporal gap between the formation of the individual complexes and that of the supercomplexes; (3) some putative respirasomes contain CoQ and cytochrome c; (4) isolated respirasomes can transfer electrons from NADH to O2, that is, they respire. Therefore, we have demonstrated the existence of a functional respirasome and propose a structural organization model that accommodates these findings.
• Bioblast editor: Gnaiger E
Selected quotes and comments
- "The mitochondrial respiratory chain (MRC) is organized as a branched chain of multiprotein complexes that oxidize reduced nicotinamide adenine dinucleotide (NADH) (complexes I, III, and IV) or reduced flavin adenine dinucleotide (FADH2) (complex II), .."
- Comment: A fundamental error is widespread, representing Complex II (CII) as the enzyme that oxidizes FADH2 (see above). In fact, CII oxidzes succinate and reduces FAD. FADH2 is not a substrate of CII (is not oxidized by CII) but is a product of CII. - See Gnaiger (2020).
- "Up to the present, the organization of the mitochondrial respiratory chain as supercomplexes was sustained solely on structural evidence but lacked functional support. .. Our observations allow us to draw an inclusive model, which we would like to call the ‘‘plasticity model’’ (Figure 7C), that substantially supports the fluid model (Figure 7A) with fundamental conceptual corrections. .. At the end, the impossibility for any of the proposals to explain the different observations may indicate that the structural organization of the mitochondrial respiratory chain is much more rich and complex than the one proposed by the two excluding models, fluid versus solid, and that the concept of mitochondrial respiratory chain should refer to a variety of functional and structural alternative ways to build up this basic cellular-housekeeping metabolic process."
- Comment: As reviewed by Rich (1984), the "solid state" and "liquid state" models are extremes of molecular organisation. "The essential figure of interest is N - the number of acceptors within range of a quinol of lifetime t" (Rich 1984).
Labels: MiParea: Respiration
Organism: Mouse Tissue;cell: Liver Preparation: Isolated mitochondria Enzyme: Supercomplex