ATP synthesis and hydrolysis by a hybrid system reconstituted from the beta-subunit of Escherichia coli F1-ATPase and beta-less chromatophores of Rhodospirillum rubrum.

Gromet-Elhanan, Zippora; Khananshvili, Daniel; Weiss, Sara; Kanazawa, Hiroshi; Futai, Masamitsu

doi:10.1016/s0021-9258(17)38918-4

Cited by 39 publications

(7 citation statements)

References 41 publications

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“…The results observed with the native RrF0F, in the presence of Ca2+ are similar to those observed with hybrid FqF] com-plexes even in the presence of Mg2+ (Gromet-Elhanan et al, 1985b;Richter et al, 1986). The main difference between the native RrF0F, and these hybrids is in their ß subunit, since they were constructed by reconstitution of /3-less R. rubrum chromatophores with Ec/3 or CF]/3.…”

Section: Discussionsupporting

confidence: 79%

“…Hybrid F0F, complexes, obtained by reconstituting /3-less R. rubrum chromatophores with Ec/3 or CF,/3, have been found to behave in the presence of Mg2+ very similarly to the native RrF0F, in the presence of Ca2+ (Gromet-Elhanan et al, 1985b;Richter et al, 1986). Moreover, as with the native Ca-ATPase, the very low capacity of the hybrid Mg-ATPase to maintain an ATP-driven H+ translocation has also been found as not due to any hybrid-induced proton leak or F, release from the membrane (Gromet- Elhanan et al, 1985b). It thus seems that the divalent cations as well as the F,-/3 subunit play an important role in the regulation of H+-coupled ATP synthesis and hydrolysis.…”

Section: Resultsmentioning

confidence: 97%

“…The observed specific behavior of the native R. rubrum chromatophore bound F0F, (RrF0F,)'-enzyme complex in the presence of Ca2+ ions is very similar to that of the hybrid FqF, complexes, formed by reconstitution of ß subunits isolated from Escherichia coli (Ec/3) or chloroplast Fr ATPase (CF,/3) into 0-less R. rubrum chromatophores (Gromet-Elhanan et al, 1985b;Richter et al, 1986). Unlike the native enzyme complex, these hybrids exhibit, even in the presence of Mg2+ ions, a rather low photophosphorylation activity and a high ATPase activity, which is not coupled to proton uptake.…”

mentioning

confidence: 74%

“…Analytical Procedures. Photophosphorylation was carried out as previously described (Gromet-Elhanan et al, 1985b), except that glucose and hexokinase were omitted and varying concentrations of divalent cations were used as indicated.…”

Section: Methodsmentioning

confidence: 99%

“…Light-dependent and ATP-dependent quenching of quinacrine (atebrin) fluorescence was determined as described by Gromet-Elhanan et al (1985b), except that MgCl2 was omitted from the initial illuminated reaction mixture.…”

Section: Methodsmentioning

confidence: 99%

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Regulation of .DELTA.~.mu.H + -coupled ATP synthesis and hydrolysis: role of divalent cations and of the F0F1-.beta. subunit

Gromet-Elhanan¹,

Weiss²

1989

Biochemistry

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The divalent cation specificity of ATP-linked reactions catalyzed by the H+-translocating F0F! ATP synthase-ATPase complex has been followed in the Rhodospirillum rubrum chromatophore bound complex. In the presence of Mg2+ and Mn2+ the complex catalyzes ATP synthesis and hydrolysis as well as ATP-driven H+ translocation, but in the presence of Ca2+ it catalyzes only ATP hydrolysis, which is not coupled to H+ tanslocation. The inability of Ca2+ to maintain the coupling process is not due to opening of a proton leak in its presence nor to any release of p! from the membrane, because (a) an identical light-induced H+ translocation is observed in the absence or presence of Ca-ATP and (b) the Ca-ATPase, as well as the Mg-and Mn-ATPase activities, is blocked by specific F0 inhibitors. These results indicate that the divalent cations play an important role in the regulation of H+-coupled ATP synthesis and hydrolysis by the F0Fj complex. Further tests suggest that their site of action is located on the Fr/3 subunit. The isolated ß subunit of the R. rubrum FqF, has been reported to contain two nucleotide binding sites, a Mg-independent and a Mg-dependent site [Gromet-Elhanan, Z., & Khananshvili, D. (1984) Biochemistry 23, 1022-1028]. Addition of Mn2+ also enables the binding of 2 mol of ATP/mol of this isolated ß subunit. But under identical conditions, Ca2+ does not enable ATP binding to this cation-dependent site and inhibits its binding in the presence of Mg2+ or Mn2+. In light of these results we propose that the binding of Mg-ATP or -ATP, but not of Ca-ATP, to the R. rubrum ¥3-ß subunit forms the trigger that opens the pathway for H+ translocation through the FqF] complex during catalysis.Electron-transport coupled ATP synthesis in respiratory and photosynthetic organisms is catalyzed by a reversible prot Supported in part by grants from the Minerva Foundation, Munich, West Germany, and from the United States-Israel Binational Science Foundation (BSF), Jerusalem, Israel. ton-translocating ATP synthase-ATPase complex that is composed of two distinct structures (Senior & Wise, 1983; Merchant & Selman, 1985): a readily solubilized catalytic ATPase sector, Fb and an intrinsic membrane sector that is involved in proton fluxes, F0. The F,-ATPase from many different sources has a 3ß3• ( subunit structure and contains 0006-2960/89/0428-3645S01.50/0 © 1989 American Chemical Society

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Section: Discussionsupporting

confidence: 79%