title: Interaction with monomeric subunit c drives insertion of ATP synthase subunit a into the membrane and primes a-c complex formation.
abstract: Subunit a is the main part of the membrane stator of the ATP synthase molecular turbine. Subunit c is the building block of the membrane rotor. We have generated two molecular fusions of a and c subunits with different orientations of the helical hairpin of subunit c. The a/c fusion protein with correct orientation of transmembrane helices was inserted into the membrane, and co-incorporated into the F(0) complex of ATP synthase with wild type subunit c. The fused c subunit was incorporated into the c-ring tethering the ATP synthase rotor to the stator. The a/c fusion with incorrect orientation of the c-helices required wild type subunit c for insertion into the membrane. In this case, the fused c subunit remained on the periphery of the c-ring and did not interfere with rotor movement. Wild type subunit a inserted into the membrane equally well with wild type subunit c and c-ring assembly mutants that remained monomeric in the membrane. These results show that interaction with monomeric subunit c triggers insertion of subunit a into the membrane, and initiates formation of the a-c complex, the ion-translocating module of the ATP synthase. Correct assembly of the ATP synthase incorporating topologically correct fusion of subunits a and c validates using this model protein for high resolution structural studies of the ATP synthase proton channel.
authors: Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
authors: Hannah E
authors: HE
authors: Pierson
authors: Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
authors: Eva-Maria E
authors: EE
authors: Uhlemann
authors: Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada. Electronic address: Oleg.Dmitriev@usask.ca.
authors: Oleg Y
authors: OY
authors: Dmitriev
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry*; D025243:Bacterial Proton-Translocating ATPases / Q000737:chemistry*; D001692:Biological Transport; D002384:Catalysis; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D008968:Molecular Conformation; D010957:Plasmids / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D006180:Proton-Translocating ATPases / Q000737:chemistry*; D011522:Protons; D011993:Recombinant Fusion Proteins / Q000737:chemistry
chemical_list: D029968:Escherichia coli Proteins; D011522:Protons; D011993:Recombinant Fusion Proteins; C074429:atpE protein, E coli; D000251:Adenosine Triphosphatases; D025243:Bacterial Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; C074428:atpB protein, E coli