F0F1-ATPase/Synthase Is Geared to the Synthesis Mode by Conformational Rearrangement of ϵ Subunit in Response to Proton Motive Force and ADP/ATP Balance

Suzuki, Toshiharu; Murakami, Toshiya; Iino, Ryota; Suzuki, Junko; Ono, Sakurako; Shirakihara, Yasuo; Yoshida, Masasuke

doi:10.1074/jbc.m307165200

Cited by 148 publications

(153 citation statements)

References 45 publications

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“…1C). This large gap was also noted recently by Yoshida's group (58). Movement of ␤Asp-380 and ⑀Ser-108 into closer proximity would likely be prohibited with ⑀ in the open state, because the upward protrusion of the C-terminal helix ⑀ of already clashes sterically with a ␤ subunit (45).…”

Section: Discussionmentioning

confidence: 95%

“…58 and Fig. 5A) or by swinging the C-terminal domain upward while retaining the antiparallel folding of the helices as we propose in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…1B. A, the extended, unfolded conformation of ⑀ proposed by Suzuki et al (58). To accommodate the ␥-⑀ disulfide (⑀135C-␥2C, not visible) observed in that study, the C-terminal helix of ⑀ is threaded between the ␤ E and ␣ E subunits, antiparallel to the N-terminal helix of ␥.…”

Section: Discussionmentioning

confidence: 99%

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Rotor/Stator Interactions of the ϵ Subunit in Escherichia coli ATP Synthase and Implications for Enzyme Regulation

Bulygin

Duncan

Cross

2004

Journal of Biological Chemistry

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Section: Discussionmentioning

confidence: 95%

“…58 and Fig. 5A) or by swinging the C-terminal domain upward while retaining the antiparallel folding of the helices as we propose in Fig.…”

Section: Discussionmentioning

confidence: 99%

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Rotor/Stator Interactions of the ϵ Subunit in Escherichia coli ATP Synthase and Implications for Enzyme Regulation

Bulygin

Duncan

Cross

2004

Journal of Biological Chemistry

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“…The maintenance of normal ATP levels in the presence of CCCP was noted previously in experiments with Y. enterocolitica 7 and is thought to be due to a regulatory mechanism that inhibits the hydrolytic activity of the ATP synthase when the membrane is deenergized 10 . Because this protective mechanism may not act instantaneously, cellular ATP levels might undergo a transient drop following CCCP treatment that would escape detection in our measurements.…”

mentioning

confidence: 88%

Energy source of flagellar type III secretion

Paul

Erhardt

Hirano

et al. 2008

Nature

290

317

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Bacterial flagella contain a specialized secretion apparatus that functions to deliver the protein subunits that form the filament and other structures to outside the membrane 1 . This apparatus is related to the injectisome used by many gram-negative pathogens and symbionts to transfer effector proteins into host cells; in both systems this export mechanism is termed 'type III' secretion 2,3 . The flagellar secretion apparatus comprises a membrane-embedded complex of about five proteins, and soluble factors, which include export-dedicated chaperones and an ATPase, FliI, that was thought to provide the energy for export 1,4 . Here we show that flagellar secretion in Salmonella enterica requires the proton motive force (PMF) and does not require ATP hydrolysis by FliI. The export of several flagellar export substrates was prevented by treatment with the protonophore CCCP, with no accompanying decrease in cellular ATP levels. Weak swarming motility and rare flagella were observed in a mutant deleted for FliI and for the nonflagellar type-III secretion ATPases InvJ and SsaN. These findings show that the flagellar secretion apparatus functions as a protondriven protein exporter and that ATP hydrolysis is not essential for type III secretion.Flagellar assembly begins with structures in the cytoplasmic membrane and proceeds through steps that add the exterior structures in a proximal-to-distal sequence (Fig. 1) 1 . Assembly of the rod, hook and filament requires the action of the secretion apparatus, which transports the needed subunits into a central channel through the structure that conducts them to their site of incorporation at the tip ( Fig. 1). Flagellar export is notably fast: in the early stages of filament growth flagellin is delivered at a rate of several 55 kDa subunits per second 5 .ATP hydrolysis by FliI was thought to provide the energy for export because mutations that delete or reduce the activity of FliI block flagellar synthesis at the stage of rod assembly 1,4,6 (Fig. 1). Homologues of FliI also occur in the type III secretion apparatus of injectisomes and are usually assumed to energize export in those systems as well. Some evidence for a different view has also been reported: it was observed that type III secretion in Yersinia enterocolitica was prevented by the protonophore CCCP 7 , and it was shown that the secretion ATPase InvC of Salmonella functions to dissociate export substrate from the chaperone 8 , a role distinct from transport itself. The energy source for type III secretion thus remains uncertain.To address the energy requirements for type III secretion, we first measured the effect of the uncoupler CCCP on flagellar export in S. enterica, assayed by accumulation of the export substrate FlgM in the medium. FlgM export was prevented by 10 mM or more CCCP (Fig. 2a). Overall cellular energy levels seemed unaffected, because cells grew normally in 10 mM CCCP (growth data not shown) and ATP levels were unchanged ( Supplementary Fig. 1). The effect was reversible: FlgM export was largely re...

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“…The ATP-driven proton-pumping activity of F 1 F 0 proteoliposomes was monitored by quenching the fluorescence of 9-amino-6-chloro-2-methoxyacridine (ACMA) as described previously (20). ATP synthesis activity was measured as described previously (36) except that the reactions were performed at 45°C in 10 mM HEPES-KOH, pH 7.5, 5 mM MgCl 2 , 100 mM KCl, 1 mM ADP, and 25 mM potassium P i . Proton …”

Section: Methodsmentioning

confidence: 99%