scholarly journals The ATP synthase γ subunit provides the primary site of activation of the chloroplast enzyme: experiments with a chloroplast-like Synechocystis 6803 mutant

1997 ◽  
Vol 323 (3) ◽  
pp. 841-845 ◽  
Author(s):  
Bea E. KRENN ◽  
Heinrich STROTMANN ◽  
Hendrika S. VAN WALRAVEN ◽  
Marijke J. C. SCHOLTS ◽  
Ruud KRAAYENHOF
Keyword(s):  
Atp Synthase ◽  
Membrane Vesicles ◽  
Enzyme Activation ◽  
Reduced Form ◽  
Synechocystis 6803 ◽  
Wild Type ◽  
Acid Base ◽  
Γ Subunit ◽  
Base Transition ◽  
Membrane Bound

The activation characteristics of the F1Fo-ATP synthase (where F1 and Fo are the hydrophilic and membrane-bound parts respectively of the enzyme) from Synechocystis 6803 wild-type and a Synechocystis 6803 mutant with a chloroplast-like insertion in the γ subunit have been studied. Activation of the ATP synthase in wild-type and mutant membrane vesicles was performed by acid–base transition-induced generation of a proton motive force (ΔH+). Since the mutant containing the regulatory segment of the chloroplast γ subunit showed thiol-modulation (typical of the chloroplast enzyme), this segment is indeed involved in the regulation of enzyme activation. It is shown that the ATP synthase from Synechocystis 6803 wild type corresponds functionally to the reduced form of the chloroplast ATP synthase, in view of the low ΔH+ required for activation of the enzyme and the high stability of the active state. Both the cyanobacterial wild-type and mutant ATP synthases can be activated by methanol, which apparently does not require the presence of the γ subunit regulatory segment.

scholarly journals Role of βAsn-243 in the Phosphate-binding Subdomain of Catalytic Sites ofEscherichia coliF1-ATPase

2004 ◽  
Vol 279 (44) ◽  
pp. 46057-46064 ◽  
Author(s):  
Zulfiqar Ahmad ◽  
Alan E. Senior
Keyword(s):  
Atpase Activity ◽  
Atp Synthase ◽  
Catalytic Mechanism ◽  
Wild Type ◽  
Phosphate Binding ◽  
Γ Subunit ◽  
Catalytic Sites ◽  
The Face ◽  
Extensive Involvement

In the catalytic mechanism of ATP synthase, phosphate (Pi) binding and release steps are believed to be correlated to γ-subunit rotation, and Pibinding is proposed to be prerequisite for binding ADP in the face of high cellular [ATP]/[ADP] ratios. In x-ray structures, residue βAsn-243 appears centrally located in the Pi-binding subdomain of catalytic sites. Here we studied the role of βAsn-243 inEscherichia coliATP synthase by mutagenesis to Ala and Asp. Mutation βN243A caused 30-fold impairment of F1-ATPase activity; 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole inhibited this activity less potently than in wild type and Piprotected from inhibition. ADP-fluoroaluminate was more inhibitory than in wild-type, but ADP-fluoroscandium was less inhibitory. βN243D F1-ATPase activity was impaired by 1300-fold and was not inhibited by ADP-fluoroaluminate or ADP-fluoroscandium. 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole activated βN243D F1-ATPase, and Pidid not affect activation. We conclude that residue βAsn-243 is not involved in Pibinding directly but is necessary for correct organization of the transition state complex through extensive involvement in hydrogen bonding to neighboring residues. It is also probably involved in orientation of the “attacking water” and of an associated second water.

scholarly journals Deleting the IF 1 -like ζ subunit from Paracoccus denitrificans ATP synthase is not sufficient to activate ATP hydrolysis

Open Biology ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 170206 ◽  
Author(s):  
Febin Varghese ◽  
James N. Blaza ◽  
Andrew J. Y. Jones ◽  
Owen D. Jarman ◽  
Judy Hirst
Keyword(s):  
Atp Synthase ◽  
Atp Hydrolysis ◽  
Paracoccus Denitrificans ◽  
Atp Synthesis ◽  
Membrane Vesicles ◽  
Inhibitor Protein ◽  
Wild Type ◽  
Efficient Energy ◽  
Inverted Membrane Vesicles ◽  
Atp Synthases

In oxidative phosphorylation, ATP synthases interconvert two forms of free energy: they are driven by the proton-motive force across an energy-transducing membrane to synthesize ATP and displace the ADP/ATP ratio from equilibrium. For thermodynamically efficient energy conversion they must be reversible catalysts. However, in many species ATP synthases are unidirectional catalysts (their rates of ATP hydrolysis are negligible), and in others mechanisms have evolved to regulate or minimize hydrolysis. Unidirectional catalysis by Paracoccus denitrificans ATP synthase has been attributed to its unique ζ subunit, which is structurally analogous to the mammalian inhibitor protein IF 1 . Here, we used homologous recombination to delete the ζ subunit from the P. denitrificans genome, and compared ATP synthesis and hydrolysis by the wild-type and knockout enzymes in inverted membrane vesicles and the F 1 -ATPase subcomplex. ATP synthesis was not affected by loss of the ζ subunit, and the rate of ATP hydrolysis increased by less than twofold, remaining negligible in comparison with the rates of the Escherichia coli and mammalian enzymes. Therefore, deleting the P. denitrificans ζ subunit is not sufficient to activate ATP hydrolysis. We close by considering our conclusions in the light of reversible catalysis and regulation in ATP synthase enzymes.

scholarly journals Biochemical and Molecular Characterization of a Na+-Translocating F1Fo-ATPase from the Thermoalkaliphilic Bacterium Clostridium paradoxum

2006 ◽  
Vol 188 (14) ◽  
pp. 5045-5054 ◽  
Author(s):  
Scott A. Ferguson ◽  
Stefanie Keis ◽  
Gregory M. Cook
Keyword(s):  
Atp Synthase ◽  
Electrical Potential ◽  
Atp Synthesis ◽  
Membrane Vesicles ◽  
Binding Motif ◽  
Sodium Ions ◽  
Membrane Bound ◽  
Transmembrane Electrical Potential ◽  
Synthase Inhibitor

ABSTRACT Clostridium paradoxum is an anaerobic thermoalkaliphilic bacterium that grows rapidly at pH 9.8 and 56°C. Under these conditions, growth is sensitive to the F-type ATP synthase inhibitor N,N′-dicyclohexylcarbodiimide (DCCD), suggesting an important role for this enzyme in the physiology of C. paradoxum. The ATP synthase was characterized at the biochemical and molecular levels. The purified enzyme (30-fold purification) displayed the typical subunit pattern for an F1Fo-ATP synthase but also included the presence of a stable oligomeric c-ring that could be dissociated by trichloroacetic acid treatment into its monomeric c subunits. The purified ATPase was stimulated by sodium ions, and sodium provided protection against inhibition by DCCD that was pH dependent. ATP synthesis in inverted membrane vesicles was driven by an artificially imposed chemical gradient of sodium ions in the presence of a transmembrane electrical potential that was sensitive to monensin. Cloning and sequencing of the atp operon revealed the presence of a sodium-binding motif in the membrane-bound c subunit (viz., Q28, E61, and S62). On the basis of these properties, the F1Fo-ATP synthase of C. paradoxum is a sodium-translocating ATPase that is used to generate an electrochemical gradient of Na+ that could be used to drive other membrane-bound bioenergetic processes (e.g., solute transport or flagellar rotation). In support of this proposal are the low rates of ATP synthesis catalyzed by the enzyme and the lack of the C-terminal region of the ε subunit that has been shown to be essential for coupled ATP synthesis.

ATP synthase from a cyanobacterial Synechocystis 6803 mutant containing the regulatory segment of the chloroplast γ subunit shows thiol modulation

1995 ◽  
Vol 23 (4) ◽  
pp. 757-760 ◽  
Author(s):  
B. E. Krenn ◽  
P. Aardewijn ◽  
H. S. Van Walraven ◽  
S. Werner-Grüne ◽  
H. Strotmann ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Synechocystis 6803 ◽  
Γ Subunit

The Rate of ATP Hydrolysis Catalyzed by Reconstituted CF0F1-Liposomes

1987 ◽  
Vol 42 (3) ◽  
pp. 231-236 ◽  
Author(s):  
Günter Schmidt ◽  
Peter Gräber
Keyword(s):  
Atp Synthase ◽  
Atp Hydrolysis ◽  
Acid Base ◽  
Chloroplast Atp Synthase ◽  
Base Transition

The conditions for optimal rates of ATP hydrolysis catalyzed by the chloroplast ATP-synthase (ATPase), CF0F1, after isolation and reconstitution into asolectin liposomes have been investi­gated. The rate of ATP hydrolysis was measured either after oxidation of CF0F1 (by incubation with iodosobenzoate) or after reduction of CFoF, (by incubation with dithiothreitol). In both cases a rate of about 1-2 ATP (CF0F1·s)-1 was observed under uncoupled conditions. If the proteoliposomes are first energized by an acid-base transition and a K+ /valinomycin diffusion poten­tial, the uncoupled rate of ATP hydrolysis is about 1-2 ATP (CF0F1 ·s) 1 for the oxidized enzyme and about 20 for the reduced species. This rate is about a factor 2 smaller than that observed in chloroplasts under the same conditions

scholarly journals The role of Zur-regulated lipoprotein A in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles in Acinetobacter baumannii

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nayeong Kim ◽  
Hyo Jeong Kim ◽  
Man Hwan Oh ◽  
Se Yeon Kim ◽  
Mi Hyun Kim ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Mutant Strain ◽  
Antimicrobial Susceptibility ◽  
Type Strain ◽  
Wild Type Strain ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Wild Type ◽  
Bacterial Morphology

Abstract Background Zinc uptake-regulator (Zur)-regulated lipoprotein A (ZrlA) plays a role in bacterial fitness and overcoming antimicrobial exposure in Acinetobacter baumannii. This study further characterized the zrlA gene and its encoded protein and investigated the roles of the zrlA gene in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles (OMVs) in A. baumannii ATCC 17978. Results In silico and polymerase chain reaction analyses showed that the zrlA gene was conserved among A. baumannii strains with 97–100% sequence homology. Recombinant ZrlA protein exhibited a specific enzymatic activity of D-alanine-D-alanine carboxypeptidase. Wild-type A. baumannii exhibited more morphological heterogeneity than a ΔzrlA mutant strain during stationary phase. The ΔzrlA mutant strain was more susceptible to gentamicin than the wild-type strain. Sizes and protein profiles of OMVs were similar between the wild-type and ΔzrlA mutant strains, but the ΔzrlA mutant strain produced 9.7 times more OMV particles than the wild-type strain. OMVs from the ΔzrlA mutant were more cytotoxic in cultured epithelial cells than OMVs from the wild-type strain. Conclusions The present study demonstrated that A. baumannii ZrlA contributes to bacterial morphogenesis and antimicrobial resistance, but its deletion increases OMV production and OMV-mediated host cell cytotoxicity.

scholarly journals Two genes, atpC1 and atpC2, for the γ subunit of Arabidopsis thaliana chloroplast ATP synthase

1991 ◽  
Vol 266 (12) ◽  
pp. 7333-7338
Author(s):  
N Inohara ◽  
A Iwamoto ◽  
Y Moriyama ◽  
S Shimomura ◽  
M Maeda ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Atp Synthase ◽  
Chloroplast Atp Synthase ◽  
Γ Subunit
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