Redox regulation of CF1-ATPase involves interplay between the γ-subunit neck region and the turn region of the βDELSEED-loop

Abstract

The soluble F1 complex of ATP synthase (FoF1) is capable of ATP hydrolysis, accomplished by the minimum catalytic core subunits α3β3γ. A special feature of cyanobacterial F1 and chloroplast F1 (CF1) is an amino acid sequence inserted in the γ-subunit. The insertion is extended slightly into the CF1 enzyme containing two additional cysteines for regulation of ATPase activity via thiol modulation. This molecular switch was transferred to a chimeric F1 by inserting the cysteine-containing fragment from spinach CF1 into a cyanobacterial γ-subunit [Y. Kim et al., redox regulation of rotation of the cyanobacterial F1-ATPase containing thiol regulation switch, J Biol Chem, 286 (2011) 9071-9078]. Under oxidizing conditions, the obtained F1 tends to lapse into an ADP-inhibited state, a common regulation mechanism to prevent wasteful ATP hydrolysis under unfavorable circumstances. However, the information flow between thiol modulation sites on the γ-subunit and catalytic sites on the β-subunits remains unclear. Here, we clarified a possible interplay for the CF1-ATPase redox regulation between structural elements of the βDELSEED-loop and the γ-subunit neck region, i.e., the most convex part of the α-helical γ-termini. Critical residues were assigned on the β-subunit, which received the conformation change signal produced by disulfide/dithiol formation on the γ-subunit. Mutant response to the ATPase redox regulation ranged from lost to hypersensitive. Furthermore, mutant cross-link experiments and inversion of redox regulation indicated that the γ-redox state might modulate the subunit interface via reorientation of the βDELSEED motif region.

The Evolutionarily Conserved Protein PHOTOSYNTHESIS AFFECTED MUTANT71 is Required for Efficient Manganese Uptake at the Thylakoid Membrane in Arabidopsis

“…In pam71, a reduced linear electron flow is evident from the reduced effective quantum yield of PSII ( Figures 3A and 3D). We propose that during the dark-light transition, the reduced linear electron flow in pam71 causes a decelerated activation of the Calvin cycle (Michelet et al, 2013) and/or ATP synthase (Nalin and McCarty, 1984;Buchert et al, 2015), both regulated by the ferredoxin/thioredoxin system (Schürmann and Buchanan, 2008). In this scenario, the resulting transient tailback (pileup) of protons in the lumen might trigger a transient NPQ increase.…”

Implications of the mitochondrial interactome of mammalian thioredoxin 2 for normal cellular function and disease

“…Trx2 interacted also covalently with the subunit d of ATP synthase that is part of the peripheral stalk connecting the F 1 and F 0 domains [147]. Although we found reports for redox regulation of the gamma subunit of the F 1 domain [148][149][150], no data were available for such a mechanism for the alpha and beta subunits. The evidence presented herein, raises this possibility which is likely to be validated by previous work in which overexpression of Trx2 in HEK293 cells was specifically affecting the activity of ATP synthase and therefore, the potential of the mitochondrial membrane [35].…”

Thiol Redox Regulation of Plant β-Carbonic Anhydrase

“…Furthermore, αCAs are zinc-binding proteins in contrast to discorin, therefore DHAR and CA activity of discorin is Zn-independent. But as described by [53] a mutation of Q114H and addition of zinc results in an increased CA activity, but decreased DHAR activity. Both observations could be an indication for a Zn-independent second function of βCA1, namely function as DHAR which should be analyzed in future studies.…”

“…Another protein usage of the H + could occur in ATP synthesis and the CO 2 evades from the thylakoids as mentioned above. Redox regulation is well-established for processes in photosynthetic electron transport, e.g., thiol switching of F-ATP synthase to control photophosphorylation [53] and cyclic electron transport via disulfide reduction in proton gradient 5-like (PGR5-like) [54]. Therefore, redox regulation of CA may be another element in redox-dependent optimization of the photosynthetic performance in plants.…”