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Updated: Aug 7, 2026

Visualization of ATP Synthase Dimers in Mitochondria by Electron Cryo-tomography
Published on: September 14, 2014
Substrate binding changes conformation of the alpha-, but not the beta-subunit of mitochondrial processing peptidase
1Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague.
Abstract:
Lifetime analysis of tryptophan fluorescence of the mitochondrial processing peptidase (MPP) from Saccharomyces cerevisiae clearly proved that substrate binding evoked a conformational change of the alpha-subunit while presence of substrate influenced neither the lifetime components nor the average lifetime of the tryptophan excited state of the beta-MPP subunit. Interestingly, lifetime analysis of tryptophan fluorescence decay of the alpha-MPP subunit revealed about 11% of steady-state fractional intensity due to the long-lived lifetime component, indicating that at least one tryptophan residue is partly buried at the hydrophobic microenvironment. Computer modeling, however, predicted none of three tryptophans, which the alpha-subunit contains, as deeply buried in the protein matrix. We conclude this as a consequence of a possible dimeric (oligomeric) structure.
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