화학공학소재연구정보센터
Biochemical and Biophysical Research Communications, Vol.509, No.1, 102-107, 2019
Mutation Q259L in subunit beta in Bacillus subtilis ATP synthase attenuates ADP-inhibition and decreases fitness in mixed cultures
The ATPase activity of H+-F0F1-ATP synthase (F0F1) is down-regulated by several mechanisms. The most universal of them found in bacterial, chloroplast and mitochondrial enzymes is non-competitive inhibition by MgADP (ADP-inhibition). When MgADP binds in a catalytic site in the absence of phosphate, the nucleotide might be trapped instead of being released and replaced by new MgATP. In this case the enzyme becomes inactivated, and MgADP release is required for re-activation. The degree of ADP-inhibition varies between different organisms: it is strong in mitochondrial and chloroplast F0F1 and in enzymes of some bacteria (including Bacillus PS3 sp., and Bacillus subtilis), but in F0F1 of Escherichia coli it is much weaker. It was shown that mutation betaGln259Leu in Bacillus PS3 F0F1 noticeably relieves its strong ADP-inhibition. In this work, we introduced the same mutation in F0F1 from B. subtilis. ADP-inhibition in the mutant F0F1 was also attenuated in comparison to the wild-type enzyme. The ATPase activity in membrane preparations was 3 fold higher in the mutant. Mutant enzyme was capable of ATP-driven proton pumping, and its ATPase activity was stimulated by dissipation of the protonmotive force, implying that the coupling efficiency between ATP hydrolysis and proton transport was not impaired by the mutation. We observed no effect of mutation on the growth rate of B. subtilis in pure cultures. However, in competition growth experiments when the wild type and the mutant strains were cultivated together in mixed cultures, the wild type strain always crowded out the mutant. To our knowledge, this is the first demonstration of the negative effect of F0F1 ADP-inhibition attenuation in vivo. (C) 2018 Elsevier Inc. All rights reserved.