The mitochondrial ATP synthase inhibitor protein binds near the C‐terminus of the F<sub>1</sub> β‐subunit

Jackson, Philip J.; Harris, David A.

doi:10.1016/0014-5793(88)80832-9

Cited by 51 publications

(28 citation statements)

References 25 publications

(35 reference statements)

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“…This β E -γ-ε cleft was the wider binding site available for entrance of the IF 1 N-terminal side into the rotor-stator interface. It is clearly demonstrated from different perspectives that the binding of the N-terminal side of IF 1 in this position interferes not only with the conformational changes of the β subunits, as proposed before [19,48], but also with the intrinsic rotation of the central stalk. Thus, we supported and proposed a novel mechanism of action for this protein that was later confirmed by the elegant crystal structure of the reconstituted dimeric F 1 -IF 1 complex [22].…”

Section: The Inhibitor Protein (If 1 ) and Its Inhibitory And Dimerizmentioning

confidence: 70%

Regulation of the F1F0-ATP Synthase Rotary Nanomotor in its Monomeric-Bacterial and Dimeric-Mitochondrial Forms

García-Trejo

Morales-Ríos

2008

J Biol Phys

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The F 1 F 0 -adenosine triphosphate (ATP) synthase rotational motor synthesizes most of the ATP required for living from adenosine diphosphate, Pi, and a proton electrochemical gradient across energy-transducing membranes of bacteria, chloroplasts, and mitochondria. However, as a reversible nanomotor, it also hydrolyzes ATP during de-energized conditions in all energy-transducing systems. Thus, different subunits and mechanisms have emerged in nature to control the intrinsic rotation of the enzyme to favor the ATP synthase activity over its opposite and commonly wasteful ATPase turnover. Recent advances in the structural analysis of the bacterial and mitochondrial ATP synthases are summarized to review the distribution and mechanism of the subunits that are part of the central rotor and regulate its gyration. In eubacteria, the ε subunit works as a ratchet to favor the rotation of the central stalk in the ATP synthase direction by extending and contracting two α-helixes of its C-terminal side and also by binding ATP with low affinity in thermophilic bacteria. On the other hand, in bovine heart mitochondria, the so-called inhibitor protein (IF 1 ) interferes with the intrinsic rotational mechanism of the central γ subunit and with the opening and closing of the catalytic β-subunits to inhibit its ATPase activity. Besides its inhibitory role, the IF 1 protein also promotes the dimerization of the bovine and rat mitochondrial enzymes, albeit it is not essential for dimerization of the yeast F 1 F 0 mitochondrial complex. High-resolution electron microscopy of the dimeric enzyme in its bovine and yeast forms shows a conical shape that is compatible with the role of the ATP synthase dimer in the formation of tubular the cristae membrane of mitochondria after further oligomerization. Dimerization of the mitochondrial ATP synthase diminishes the rotational drag of the central rotor that would decrease the coupling efficiency between rotation of the central stalk and ATP synthesis taking place at the F 1 portion. In addition, F 1 F 0 dimerization and its further oligomerization also increase the stability of the enzyme to natural or experimentally induced destabilizing conditions.

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Section: The Inhibitor Protein (If 1 ) and Its Inhibitory And Dimerizmentioning

confidence: 70%

Regulation of the F1F0-ATP Synthase Rotary Nanomotor in its Monomeric-Bacterial and Dimeric-Mitochondrial Forms

García-Trejo

Morales-Ríos

2008

J Biol Phys

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“…In mitochondria, ATPase activity is regulated by the natural inhibitor protein IF 1 , which binds to the ATP synthase in a pH-dependent manner. Crosslinking studies suggest an interaction between IF 1 and the C-terminal region of the ␤ subunit (21). No homologue of IF 1 has been found in either chloroplasts or bacteria.…”

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confidence: 99%

Inhibition of ATP Hydrolysis by Thermoalkaliphilic F ₁ F _o -ATP Synthase Is Controlled by the C Terminus of the ε Subunit

Keis

Stocker²,

Dimroth³

et al. 2006

J Bacteriol

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Bacillus sp. strain TA2.A1, this activity is intrinsic to the F 1 moiety. To study the mechanism of ATPase inhibition, we developed a heterologous expression system in Escherichia coli to produce TA2F 1 complexes from this thermoalkaliphile. Like the native F 1 F o -ATP synthase, the recombinant TA2F 1 was blocked in ATP hydrolysis activity, and this activity was stimulated by the detergent lauryldimethylamine oxide. To determine if the C-terminal domain of the subunit acts as an inhibitor of ATPase activity and if an electrostatic interaction plays a role, a TA2F 1 mutant with either a truncated subunit [i.e., TA2F 1 ( ⌬C )] or substitution of basic residues in the second ␣-helix of with nonpolar alanines [i.e., TA2F 1 ( 6A )] was constructed. Both mutants showed ATP hydrolysis activity at low and high concentrations of ATP. Treatment of the purified F 1 F o -ATP synthase and TA2F 1 ( WT ) complex with proteases revealed that the subunit was resistant to proteolytic digestion. In contrast, the subunit of TA2F 1 ( 6A ) was completely degraded by trypsin, indicating that the C-terminal arm was in a conformation where it was no longer protected from proteolytic digestion. In addition, ATPase activity was not further activated by protease treatment when compared to the untreated control, supporting the observation that was responsible for inhibition of ATPase activity. To study the effect of the alanine substitutions in the subunit in the entire holoenzyme, we reconstituted recombinant TA2F 1 complexes with F 1 -stripped native membranes of strain TA2.A1. The reconstituted TA2F o F 1 ( WT ) was blocked in ATP hydrolysis and exhibited low levels of ATP-driven proton pumping consistent with the F 1 F o -ATP synthase in native membranes. Reconstituted TA2F o F 1 ( 6A ) exhibited ATPase activity that correlated with increased ATP-driven proton pumping, confirming that the subunit also inhibits ATPase activity of TA2F o F 1 .

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“…While it seems intuitive that this hydrolase inhibition can prevent wasteful ATP hydrolysis during ischemia, this inhibition of the F 1 F 0 ATP hydrolase is not complete as F 1 F 0 ATPase inhibitors such as oligomycin and aurovertin B reduce the rate of ATP decline, suggesting incomplete inhibition of the hydrolase activity [9][10][11][12]. This will be discussed in more detail later.The mechanism of IF-1 inhibition is via trapping of adenine nucleotides within the catalytic sites of F 1 [43], requiring ATP hydrolysis and the presence of a divalent cation, particularly Mg 2+ , and works by prevention of rotation of the catalytic domains around the stalk [44][45][46].Further confusing the issue is that IF-1 activity and expression vary by species. IF-1 in the heart is expressed differently in several mammalian species, and this has been subdivided into "fast heart rate species" (rat, mice, and birds) that express low levels of IF-1 and "slow heart rate species" (dogs and rabbits) that express high levels of IF- 10,[47][48][49].…”

mentioning

confidence: 99%

Pharmacological Profile of the Selective Mitochondrial F₁F₀ ATP Hydrolase Inhibitor BMS‐199264 in Myocardial Ischemia

Grover¹,

Malm²

2008

Cardiovascular Therapeutics

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The mitochondrial F 1 F 0 ATP synthase is responsible for the majority of ATP production in mammals and does this through a rotary catalytic mechanism. Studies show that the F 1 F 0 ATP synthase can switch to an ATP hydrolase, and this occurs under conditions seen during myocardial ischemia. This ATP hydrolysis causes wasting of ATP that does not produce work. The degree of ATP inefficiently hydrolyzed during ischemia may be as high as 50-90% of the total. A naturally occurring, reversible inhibitor (IF-1) of the hydrolase activity is in the mitochondria, and it has a pH optimum of 6.8. Based on studies with the nonselective (inhibit both synthase and hydrolase activity) inhibitors aurovertin B and oligomycin B reduce the rate of ATP depletion during ischemia, showing that IF-1 does not completely block hydrolase activity. Oligmycin and aurovertin cannot be used for treating myocardial ischemia as they will reduce ATP production in healthy tissue. We generated a focused structureactivity relationship, and several compounds were identified that selectively inhibited the F 1 F 0 ATP hydrolase activity while having no effect on synthase function. One compound, BMS-199264 had no effect on F 1 F 0 ATP synthase function in submitochondrial particles while inhibiting hydrolase function, unlike oligomycin that inhibits both. BMS-199264 selectively inhibited ATP decline during ischemia while not affecting ATP production in normoxic and reperfused hearts. BMS-191264 also reduced cardiac necrosis and enhanced the recovery of contractile function following reperfusion. These data also suggest that the reversal of the synthase and hydrolase activities is not merely a chemical reaction run in reverse. IntroductionMyocardial ischemia is caused by an oxygen supply/demand imbalance. The degree of coronary occlusion will give differential clinical presentations and different therapeutic modes of treatment. Chronic stable angina is myocardial ischemia seen only upon increased oxygen demand (increased exertion) as the coronary stenosis alone will not cause pain or ST-segment abnormalities at rest. Resolution of symptoms often occurs after cessation of the increased exertion. Numerous therapeutics can resolve the symptoms of stable angina pectoris and these include nitrates, calcium antagonists, and β-adrenoceptor blockers [1][2][3].Severe myocardial ischemia causing necrosis or infarction has been difficult to effectively treat pharmacologically. Surgical intervention is the most commonly employed treatment because of its efficacy, along with agents such as aspirin, which are efficacious in secondary prevention of myocardial infarction. Many types of agents are efficacious in reducing infarct size or showing cardioprotection in animal models such as in dog and rat infarct size models and isolated rat hearts [1][2][3][4][5][6]. These agents include calcium antagonists, β-adrenoceptor blockers, preconditioning, and ATPsensitive potassium channel (K ATP ) openers. These agents are associated with preservation of ATP in ischemic myocyt...

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The mitochondrial ATP synthase inhibitor protein binds near the C‐terminus of the F₁ β‐subunit

Cited by 51 publications

References 25 publications

Regulation of the F1F0-ATP Synthase Rotary Nanomotor in its Monomeric-Bacterial and Dimeric-Mitochondrial Forms

Regulation of the F1F0-ATP Synthase Rotary Nanomotor in its Monomeric-Bacterial and Dimeric-Mitochondrial Forms

Inhibition of ATP Hydrolysis by Thermoalkaliphilic F ₁ F _o -ATP Synthase Is Controlled by the C Terminus of the ε Subunit

Pharmacological Profile of the Selective Mitochondrial F₁F₀ ATP Hydrolase Inhibitor BMS‐199264 in Myocardial Ischemia

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The mitochondrial ATP synthase inhibitor protein binds near the C‐terminus of the F1 β‐subunit

Cited by 51 publications

References 25 publications

Regulation of the F1F0-ATP Synthase Rotary Nanomotor in its Monomeric-Bacterial and Dimeric-Mitochondrial Forms

Regulation of the F1F0-ATP Synthase Rotary Nanomotor in its Monomeric-Bacterial and Dimeric-Mitochondrial Forms

Inhibition of ATP Hydrolysis by Thermoalkaliphilic F 1 F o -ATP Synthase Is Controlled by the C Terminus of the ε Subunit

Pharmacological Profile of the Selective Mitochondrial F1F0 ATP Hydrolase Inhibitor BMS‐199264 in Myocardial Ischemia

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The mitochondrial ATP synthase inhibitor protein binds near the C‐terminus of the F₁ β‐subunit

Inhibition of ATP Hydrolysis by Thermoalkaliphilic F ₁ F _o -ATP Synthase Is Controlled by the C Terminus of the ε Subunit

Pharmacological Profile of the Selective Mitochondrial F₁F₀ ATP Hydrolase Inhibitor BMS‐199264 in Myocardial Ischemia