title: 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.
authors: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259-R1-8, Midori-ku, Yokohama 226-8503, Japan.
authors: Felix
authors: F
authors: Buchert
authors: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259-R1-8, Midori-ku, Yokohama 226-8503, Japan; Imaging Research Division, Bio-AFM Frontier Research Center, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan.
authors: Hiroki
authors: H
authors: Konno
authors: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259-R1-8, Midori-ku, Yokohama 226-8503, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo 102-0075, Japan. Electronic address: thisabor@res.titech.ac.jp.
authors: Toru
authors: T
authors: Hisabori
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D025222:Chloroplast Proton-Translocating ATPases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology*; D000458:Cyanobacteria / Q000201:enzymology*; D004926:Escherichia coli / Q000235:genetics; D006868:Hydrolysis; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018724:Spinacia oleracea / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D011993:Recombinant Fusion Proteins; D013438:Sulfhydryl Compounds; D000255:Adenosine Triphosphate; D025222:Chloroplast Proton-Translocating ATPases; D006180:Proton-Translocating ATPases
keywords: ATPase redox regulation; Chloroplast ATP synthase; Cysteine‐mediated cross‐linking; Subunit interaction; Thiol labeling; βDELSEED-loop