Characteristics of the combination of inhibitory magnesium and azide with the F1 ATPase from chloroplasts

Murataliev, Marat B.; Milgrom, Yakov M.; Boyer, Paul D.

doi:10.1021/bi00098a004

Cited by 47 publications

(42 citation statements)

References 39 publications

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“…The thylakoid PMF can be established either by photo electron transport in light or by ATP synthase (CF1/CF0) proton pumping via ATP hydrolysis. Although azide inhibits SECA, it also inhibits ATP synthase (Murataliev et al, 1991). Thus, the inhibition by azide in dark but not in light (Fig.…”

Section: Integration Of Thylakoid Protein Substratesmentioning

confidence: 86%

Identification of Putative Substrates of SEC2, a Chloroplast Inner Envelope Translocase

Martin

Aldama

et al. 2017

Plant Physiol.

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Most chloroplast proteins are synthesized in the cytosol and imported into chloroplasts. Many imported proteins are further targeted to the thylakoid membrane and lumen by the SEC1, TAT, or SRP/ALB3 translocases. Others are targeted to the inner chloroplast envelope membrane by undescribed translocases. Recently, a second SEC system (SEC2) consisting of SCY2, SECE2, and SECA2 was found in the chloroplast envelope. Null mutants of SCY2 in Arabidopsis (Arabidopsis thaliana) exhibit a severe embryo-lethal phenotype. To investigate the function of the SEC2 system in plants, we used inducible RNA interference to knock down SCY2 in Arabidopsis. Seedlings cultured with inducer were chlorotic with aberrant chloroplasts and undeveloped thylakoids, indicating an essential role for SCY2 in chloroplast biogenesis beyond embryo development. In SCY2 down-regulated seedlings, several thylakoid membrane proteins, including SCY1, ALB3, and TATC, and inner envelope membrane proteins, including TIC40, TIC110, and FTSH12, were reduced substantially, suggesting that they may be SEC2 substrates. Additional insight was achieved by the in vitro reconstitution of protein integration into chloroplast membranes. The results show that SCY1 and ALB3 target directly to the thylakoid membrane and are likely independent of SEC2. FTSH12 was integrated into the envelope membrane in a coupled import-integration reaction that was impaired by the SECA inhibitor sodium azide. The stromal intermediate of TIC40 integrated into the envelope in a reaction that was largely inhibited when antibodies against epitope-tagged SCY2 or SECE2 were applied. These data demonstrate that the SEC2 translocase likely integrates a subset of inner envelope membrane proteins, such as FTSH12 and TIC40.

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Section: Integration Of Thylakoid Protein Substratesmentioning

confidence: 86%

Identification of Putative Substrates of SEC2, a Chloroplast Inner Envelope Translocase

Martin

Aldama

et al. 2017

Plant Physiol.

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“…The purified Gln-␤185 and Cys-␤185 F 1 -ATPases also exhibited no multisite catalysis. Cross and co-workers (27) showed recently that E. coli F 1 -ATPase, similar to chloroplast or mitochondrial F 1 (30), is inhibited by the catalytic site-bound Mg⅐ADP. They proposed that the effect of Mg⅐ADP should be considered before kinetic results are interpreted.…”

Section: Discussionmentioning

confidence: 99%

“…Enzymes-Azide is known to inhibit multisite catalysis of F 1 -ATPase by stabilizing F 1 ⅐Mg⅐ADP complex (30), and its inhibition is dependent on the Mg 2ϩ concentration, although azide has no effect on unisite catalysis (22). Thus it was reasonable to assume that multisite catalyses with the S-carboxymethyl-␤185 and Asp-␤185 enzymes may exhibit different azide sensitivities from that of the wild type because the two enzymes exhibited altered Mg 2ϩ inhibition (Fig.…”

Section: Effect Of Azide On the S-carboxymethyl-␤185 And Asp-␤185mentioning

confidence: 99%

β Subunit Glu-185 of Escherichia coli H+-ATPase (ATP Synthase) Is an Essential Residue for Cooperative Catalysis

Omote

Park

et al. 1995

Journal of Biological Chemistry

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Glu-␤185 of the Escherichia coli H؉ -ATPase (ATP synthase) ␤ subunit was replaced by 19 different amino acid residues. The rates of multisite (steady state) catalysis of all the mutant membrane ATPases except Asp-␤185 were less than 0.2% of the wild type one; the Asp-␤185 enzyme exhibited 15% (purified) and 16% (membrane-bound) ATPase activity. The purified inactive Cys-␤185 F 1 -ATPase recovered substantial activity after treatment with iodoacetate in the presence of MgCl 2 ; maximal activity was obtained upon the introduction of about 3 mol of carboxymethyl residues/mol of F 1 . The divalent cation dependences of the S-carboxymethyl-␤185 and Asp-␤185 ATPase activities were altered from that of the wild type. The Asp-␤185, Cys-␤185, S-carboxymethyl-␤185, and Gln-␤185 enzymes showed about 130, 60, 20, and 50% of the wild type unisite catalysis rates, respectively. The S-carboxymethyl-␤185 and Asp-␤185 enzymes showed altered divalent cation sensitivities, and the S-carboxymethyl-␤185 enzyme showed no Mg 2؉ inhibition. Unlike the wild type, the two mutant enzymes showed low sensitivities to azide, which stabilizes the enzyme Mg⅐ADP complex. These results suggest that Glu-␤185 may form a Mg 2؉ binding site, and its carboxyl moiety is essential for catalytic cooperativity. Consistent with this model, the bovine glutamate residue corresponding to Glu-␤185 is located close to the catalytic site in the higher order structure (Abrahams, J. P., Leslie, A. G. W., Lutter, R., and Walker, J. E. (1994) Nature 370, 621-628).The H ϩ -ATPase (ATP synthase) of Escherichia coli synthesizes ATP similar to those of mitochondria or chloroplasts (see Refs. 1-4 for reviews). The catalytic site of the enzyme is in the ␤ subunit of the membrane extrinsic F 1 sector. Studies on mutant enzymes indicated that Lys-␤155 and Thr-␤156 in the ␤ subunit phosphate loop or conserved glycine-rich sequence (Gly-Gly-Ala-Gly-Val-Gly-Lys-Thr, residues 149 -156; conserved residues underlined) and Glu-␤181 and Arg-␤182 in the conserved Gly-Glu-Arg sequence (residues 180 -182) are essential catalytic residues (5-7). Affinity labeling with ATP analogues indicated that Lys-␤155 bound the ␤ and ␥ phosphate moiety of ATP (8). The crystal structure (9) of the bovine F 1 sector reported recently is essentially consistent with these results.The purified F 1 (␣ 3 ␤ 3 ␥␦⑀ or F 1 -ATPase) hydrolyzes ATP through unisite (single site) or multisite (steady state) catalysis. The multisite rate is 10 5 -10 6 -fold faster than the unisite one due to the cooperativity of the multiple catalytic sites (10, 11). Conformational transmission for cooperativity may be initiated from a specific region(s) or residue(s) in the single catalytic site of the ␤ subunit. Mutations near catalytic site residues often dramatically lower the multisite rate without changing unisite catalysis (6, 11, 12), possibly due to the defective conformational transmission between catalytic sites essential for the catalytic cooperativity. However, the role of a specific residue or region for the coopera...

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“…Azide also inhibits the ATP hydrolase activity of the mitochondrial F-ATPase but not its synthetic activity. It has a similar effect on F-ATPases in eubacteria and chloroplasts (4)(5)(6)(7). Like the other respiratory complexes, the F-ATPase is embedded in the inner membranes of mitochondria.…”

mentioning

confidence: 97%

“…It has been proposed that this inhibitory effect of ADP⅐Mg 2ϩ is enhanced by azide (5,6,22,24). Another explanation that has been advanced to explain the inhibitory effect of azide is that it blocks cooperation between catalytic sites (26,27).…”

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confidence: 99%

How azide inhibits ATP hydrolysis by the F-ATPases

Bowler

Montgomery

Leslie

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

229

180

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In the structure of bovine F1-ATPase determined at 1.95-Å resolution with crystals grown in the presence of ADP, 5 -adenylylimidodiphosphate, and azide, the azide anion interacts with the ␤-phosphate of ADP and with residues in the ADP-binding catalytic subunit, ␤DP. It occupies a position between the catalytically essential amino acids, ␤-Lys-162 in the P loop and the ''arginine finger'' residue, ␣-Arg-373, similar to the site occupied by the ␥-phosphate in the ATP-binding subunit, ␤TP. Its presence in the ␤DP-subunit tightens the binding of the side chains to the nucleotide, enhancing its affinity and thereby stabilizing the state with bound ADP. This mechanism of inhibition appears to be common to many other ATPases, including ABC transporters, SecA, and DNA topoisomerase II␣. It also explains the stimulatory effect of azide on ATP-sensitive potassium channels by enhancing the binding of ADP.mitochondria ͉ oxidative phosphorylation ͉ inhibition ͉ mechanism

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Characteristics of the combination of inhibitory magnesium and azide with the F1 ATPase from chloroplasts

Cited by 47 publications

References 39 publications

Identification of Putative Substrates of SEC2, a Chloroplast Inner Envelope Translocase

Identification of Putative Substrates of SEC2, a Chloroplast Inner Envelope Translocase

β Subunit Glu-185 of Escherichia coli H+-ATPase (ATP Synthase) Is an Essential Residue for Cooperative Catalysis

How azide inhibits ATP hydrolysis by the F-ATPases

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