ИСТИНА

ATP synthase is a key enzyme in mitochondrial bioenergetics. Typically, it utilizes the energy of transmembrane proton potential difference, maintained by the respiratory chain, to synthesize ATP. However, under membrane de-energization, ATP synthase can hydrolyze ATP. This ATPase activity can significantly decrease intracellular ATP levels and thus requires strict regulation. A common regulatory mechanism is non-competitive inhibition of the enzyme ATPase activity by Mg-ADP (ADP-inhibition) [1]. Certain mutations are known to affect the extent of ADP-inhibition; one of them is 𝛾M23K, previously studied in Rhodobacter capsulatus, Bacillus sp. PS3 and Escherichia coli. In these organisms, the M23K mutation has been shown to enhance ADP-inhibition [2,3]. Here, we have obtained a yeast strain with 𝛾M23K mutation using the CRISPR-Cas system. Measurements of ATPase activity of isolated mitochondria and submitochondrial particles have shown the increased level of ADP-inhibition. The inhibitory effect of ADP added to the ATPase reaction was more pronounced in samples obtained from the mutant strain in comparison with a parent strain. When ATPase activity was measured in the ATP-regenerating system, the mutant demonstrated a long lag period after adding ATP in the sample, which may also mean that ADP-inhibition in the mutant enzyme is enhanced. On a physiological level, the mutation resulted in a decrease in maximal growth rate (𝜇) both for Rho+ (with mtDNA) and Rho0 (without mtDNA) cells. However, if we used starved 7-day stationary cultures for inoculation, the mutant Rho0 strain had increased 𝜇 in comparison with wild-type Rho0 cells. The work is supported by Russian Science Foundation grant 20-14-00268.