ИСТИНА

One of the promising strategies to improve ethanol production in yeast is enforced ATP wasting. It was shown that heterologous expression of ATP hydrolysing F1-portion of bacterial FOF1 ATP synthase in Saccharomyces cerevisiae cells increases ethanol volumetric productivity up to 111% [1]. The native FOF1 ATP synthase of S. cerevisiae is also capable of ATP hydrolysis, but this activity is suppressed by two mechanisms: a noncompetitive inhibition by MgADP and two protein inhibitors Inh1p and Stf1p. In this work, we used mutagenesis to weaken these inhibitory mechanisms, and investigated their biochemical and physiological impact. To attenuate MgADP inhibition, we introduced a point mutation, Q263L, into β subunit of FOF1. The mutant strain grew slower and had a longer lag period preceding exponential growth phase after starvation. However, in yeast lacking mitochondrial DNA (ρ0) the effect of MgADP inhibition weakening was reversed: the βQ263L ρ0 mutant grew faster than the wild-type ρ0 yeast [2]. To examine the physiological role of Inh1p and Stf1p, we used the cells in which these factors were fused to green fluorescent protein (GFP). During the post-diauxic phase, the cells formed two subpopulations distinct in Inh1p-GFP and Stf1p-GFP concentration. Upon exit from the post-diauxic phase, the cells with high levels of Inh1-GFP started growing earlier than cells devoid of Inh1-GFP. However, the genetic deletion of Inh1p and Stf1p did not result in any significant changes in cell growth. This result points to a redundancy of the mechanisms preventing uncontrolled ATP hydrolysis by yeast F1 [3]. The work is supported by Russian Science Foundation grant 20-14-00268. [1] A. Zahoor et al., Biotechnology for Biofuels, 13 (2020) 185. [2] A. Lapashina et al., BBA Bioenergetics, 1863 (2022) 148544. [3] K. Galkina et al., Frontiers in Microbiology, 13 (2022) 816622.