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Functional importance of αAsp-350 in the catalytic sites of Escherichia coli ATP synthase. Arch Biochem Biophys 2019; 672:108050. [PMID: 31330132 DOI: 10.1016/j.abb.2019.07.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 07/10/2019] [Accepted: 07/18/2019] [Indexed: 12/21/2022]
Abstract
Negatively charged residue αAsp-350 of the highly conserved VISIT-DG sequence is required for Pi binding and maintenance of the phosphate-binding subdomain in the catalytic sites of Escherichia coli F1Fo ATP synthase. αAsp-350 is situated in close proximity, 2.88 Å and 3.5 Å, to the conserved known phosphate-binding residues αR376 and βR182. αD350 is also in close proximity, 1.3 Å, to another functionally important residue αG351. Mutation of αAsp-350 to Ala, Gln, or Arg resulted in substantial loss of oxidative phosphorylation and reduction in ATPase activity by 6- to 16-fold. The loss of the acidic side chain in the form of αD350A, αD350Q, and αD350R caused loss of Pi binding. While removal of Arg in the form of αR376D resulted in the loss of Pi binding, the addition of Arg in the form of αG351R did not affect Pi binding. Our data demonstrates that αD350R helps in the proper orientation of αR376 and βR182 for Pi binding. Fluoroaluminate, fluoroscandium, and sodium azide caused almost complete inhibition of wild type enzyme and caused variable inhibition of αD350 mutant enzymes. NBD-Cl (4-chloro-7-nitrobenzo-2-oxa-1, 3-diazole) caused complete inhibition of wild type enzyme while some residual activity was left in mutant enzymes. Inhibition characteristics supported the conclusion that NBD-Cl reacts in βE (empty) catalytic sites. Phosphate protected against NBD-Cl inhibition of wild type and αG351R mutant enzymes but not inhibition of αD350A, αD350Q, αD350R, or αR376D mutant enzymes. These results demonstrate that αAsp-350 is an essential residue required for phosphate binding, through its interaction with αR376 and βR182, for normal function of phosphate binding subdomain and for transition state stabilization in ATP synthase catalytic sites.
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ATP synthase from Trypanosoma brucei has an elaborated canonical F 1-domain and conventional catalytic sites. Proc Natl Acad Sci U S A 2018; 115:2102-2107. [PMID: 29440423 DOI: 10.1073/pnas.1720940115] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The structures and functions of the components of ATP synthases, especially those subunits involved directly in the catalytic formation of ATP, are widely conserved in metazoans, fungi, eubacteria, and plant chloroplasts. On the basis of a map at 32.5-Å resolution determined in situ in the mitochondria of Trypanosoma brucei by electron cryotomography, it has been proposed that the ATP synthase in this species has a noncanonical structure and different catalytic sites in which the catalytically essential arginine finger is provided not by the α-subunit adjacent to the catalytic nucleotide-binding site as in all species investigated to date, but rather by a protein, p18, found only in the euglenozoa. A crystal structure at 3.2-Å resolution of the catalytic domain of the same enzyme demonstrates that this proposal is incorrect. In many respects, the structure is similar to the structures of F1-ATPases determined previously. The α3β3-spherical portion of the catalytic domain in which the three catalytic sites are found, plus the central stalk, are highly conserved, and the arginine finger is provided conventionally by the α-subunits adjacent to each of the three catalytic sites found in the β-subunits. Thus, the enzyme has a conventional catalytic mechanism. The structure differs from previous described structures by the presence of a p18 subunit, identified only in the euglenozoa, associated with the external surface of each of the three α-subunits, thereby elaborating the F1-domain. Subunit p18 is a pentatricopeptide repeat (PPR) protein with three PPRs and appears to have no function in the catalytic mechanism of the enzyme.
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Sánchez-Vásquez L, González-Halphen D. TOPOLOGÍA Y FUNCIÓN DE LAS SUBUNIDADES INTRÍNSECAS DE LA MEMBRANA DE LAS F 1 F O -ATP SINTASA MITOCONDRIALES. TIP REVISTA ESPECIALIZADA EN CIENCIAS QUÍMICO-BIOLÓGICAS 2017. [DOI: 10.1016/j.recqb.2017.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Zhao C, Syed H, Hassan SS, Singh VK, Ahmad Z. Functional importance of αIle-346 and αIle-348 in the catalytic sites of Escherichia coli ATP synthase. Arch Biochem Biophys 2016; 592:27-37. [PMID: 26775572 DOI: 10.1016/j.abb.2016.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 01/09/2016] [Accepted: 01/11/2016] [Indexed: 11/16/2022]
Abstract
We studied the functional role of highly conserved VISIT-DG sequence residues αIle-346 and αIle-348 in the catalytic sites of Escherichia coli F1Fo ATP synthase. αIle-346 is in close proximity, 2.98 and 3.63 Å, to the two known phosphate binding residues αR376 and βR182; αIle-348 is situated within 3.66 Å from βR182. Single or double mutants of both αI346 and αI348 resulted in a variable loss of oxidative phosphorylation and ATPase activity. Azide, fluoroaluminate, and fluoroscandium caused insignificant to significant inhibition of mutants. Whereas the wild-type enzyme was completely inhibited by NBD-Cl (7-chloro-4-nitrobenzo-2-oxa-1, 3-diazole), a variable extent of inhibition was observed for αI346 and αI348 mutants. MgPi protection against NBD-Cl induced inhibition of wild-type, αI346, and αI348 demonstrated that, although strongly conserved, αI346 and αI348 have no direct role in phosphate binding. Insertion of Arginine in the form of αI346R/βR182A, αI346R/αR376A, or αI348R/βR182A was able to compensate for the absence of known phosphate-binding Arginine residues βR182 and αR376. Results also suggest that αIle-346 and αIle-348 seem to have functional importance in upholding the phosphate-binding subdomain and transition state stabilization in the catalytic sites of E. coli ATP synthase.
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Affiliation(s)
- Chao Zhao
- Department of Biochemistry, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
| | - Hiba Syed
- Department of Biochemistry, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
| | - Sherif S Hassan
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA; Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Vineet K Singh
- Department of Microbiology & Immunology, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
| | - Zulfiqar Ahmad
- Department of Biochemistry, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA.
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Structure of ATP synthase from Paracoccus denitrificans determined by X-ray crystallography at 4.0 Å resolution. Proc Natl Acad Sci U S A 2015; 112:13231-6. [PMID: 26460036 PMCID: PMC4629361 DOI: 10.1073/pnas.1517542112] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The structure of the intact ATP synthase from the α-proteobacterium Paracoccus denitrificans, inhibited by its natural regulatory ζ-protein, has been solved by X-ray crystallography at 4.0 Å resolution. The ζ-protein is bound via its N-terminal α-helix in a catalytic interface in the F1 domain. The bacterial F1 domain is attached to the membrane domain by peripheral and central stalks. The δ-subunit component of the peripheral stalk binds to the N-terminal regions of two α-subunits. The stalk extends via two parallel long α-helices, one in each of the related b and b' subunits, down a noncatalytic interface of the F1 domain and interacts in an unspecified way with the a-subunit in the membrane domain. The a-subunit lies close to a ring of 12 c-subunits attached to the central stalk in the F1 domain, and, together, the central stalk and c-ring form the enzyme's rotor. Rotation is driven by the transmembrane proton-motive force, by a mechanism where protons pass through the interface between the a-subunit and c-ring via two half-channels in the a-subunit. These half-channels are probably located in a bundle of four α-helices in the a-subunit that are tilted at ∼30° to the plane of the membrane. Conserved polar residues in the two α-helices closest to the c-ring probably line the proton inlet path to an essential carboxyl group in the c-subunit in the proton uptake site and a proton exit path from the proton release site. The structure has provided deep insights into the workings of this extraordinary molecular machine.
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On the Mg2+ binding site of the ε subunit from bacterial F-type ATP synthases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1101-12. [DOI: 10.1016/j.bbabio.2015.05.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 05/20/2015] [Accepted: 05/22/2015] [Indexed: 11/19/2022]
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Morales-Ríos E, Montgomery MG, Leslie AGW, García-Trejo JJ, Walker JE. Structure of a catalytic dimer of the α- and β-subunits of the F-ATPase from Paracoccus denitrificans at 2.3 Å resolution. Acta Crystallogr F Struct Biol Commun 2015; 71:1309-17. [PMID: 26457523 PMCID: PMC4601596 DOI: 10.1107/s2053230x15016076] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 08/27/2015] [Indexed: 02/02/2023] Open
Abstract
The structures of F-ATPases have predominantly been determined from mitochondrial enzymes, and those of the enzymes in eubacteria have been less studied. Paracoccus denitrificans is a member of the α-proteobacteria and is related to the extinct protomitochondrion that became engulfed by the ancestor of eukaryotic cells. The P. denitrificans F-ATPase is an example of a eubacterial F-ATPase that can carry out ATP synthesis only, whereas many others can catalyse both the synthesis and the hydrolysis of ATP. Inhibition of the ATP hydrolytic activity of the P. denitrificans F-ATPase involves the ζ inhibitor protein, an α-helical protein that binds to the catalytic F1 domain of the enzyme. This domain is a complex of three α-subunits and three β-subunits, and one copy of each of the γ-, δ- and ℇ-subunits. Attempts to crystallize the F1-ζ inhibitor complex yielded crystals of a subcomplex of the catalytic domain containing the α- and β-subunits only. Its structure was determined to 2.3 Å resolution and consists of a heterodimer of one α-subunit and one β-subunit. It has no bound nucleotides, and it corresponds to the `open' or `empty' catalytic interface found in other F-ATPases. The main significance of this structure is that it aids in the determination of the structure of the intact membrane-bound F-ATPase, which has been crystallized.
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Affiliation(s)
- Edgar Morales-Ríos
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, England
| | - Martin G. Montgomery
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, England
| | - Andrew G. W. Leslie
- The Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, England
| | - José J. García-Trejo
- Departmento de Biología, Facultad Química, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - John E. Walker
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, England
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8
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Morales-Rios E, Watt IN, Zhang Q, Ding S, Fearnley IM, Montgomery MG, Wakelam MJO, Walker JE. Purification, characterization and crystallization of the F-ATPase from Paracoccus denitrificans. Open Biol 2015; 5:150119. [PMID: 26423580 PMCID: PMC4593670 DOI: 10.1098/rsob.150119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The structures of F-ATPases have been determined predominantly with mitochondrial enzymes, but hitherto no F-ATPase has been crystallized intact. A high-resolution model of the bovine enzyme built up from separate sub-structures determined by X-ray crystallography contains about 85% of the entire complex, but it lacks a crucial region that provides a transmembrane proton pathway involved in the generation of the rotary mechanism that drives the synthesis of ATP. Here the isolation, characterization and crystallization of an integral F-ATPase complex from the α-proteobacterium Paracoccus denitrificans are described. Unlike many eubacterial F-ATPases, which can both synthesize and hydrolyse ATP, the P. denitrificans enzyme can only carry out the synthetic reaction. The mechanism of inhibition of its ATP hydrolytic activity involves a ζ inhibitor protein, which binds to the catalytic F₁-domain of the enzyme. The complex that has been crystallized, and the crystals themselves, contain the nine core proteins of the complete F-ATPase complex plus the ζ inhibitor protein. The formation of crystals depends upon the presence of bound bacterial cardiolipin and phospholipid molecules; when they were removed, the complex failed to crystallize. The experiments open the way to an atomic structure of an F-ATPase complex.
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Affiliation(s)
- Edgar Morales-Rios
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Ian N. Watt
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | | | - Shujing Ding
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Ian M. Fearnley
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Martin G. Montgomery
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | | | - John E. Walker
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK,e-mail:
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Steel BC, Nord AL, Wang Y, Pagadala V, Mueller DM, Berry RM. Comparison between single-molecule and X-ray crystallography data on yeast F1-ATPase. Sci Rep 2015; 5:8773. [PMID: 25753753 PMCID: PMC4894397 DOI: 10.1038/srep08773] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 01/29/2015] [Indexed: 12/02/2022] Open
Abstract
Single molecule studies in recent decades have elucidated the full chemo-mechanical cycle of F1-ATPase, mostly based on F1 from thermophilic bacteria. In contrast, high-resolution crystal structures are only available for mitochondrial F1. Here we present high resolution single molecule rotational data on F1 from Saccharomyces cerevisiae, obtained using new high throughput detection and analysis tools. Rotational data are presented for the wild type mitochondrial enzyme, a “liver” isoform, and six mutant forms of yeast F1 that have previously been demonstrated to be less efficient or partially uncoupled. The wild-type and “liver” isoforms show the same qualitative features as F1 from Escherichia coli and thermophilic bacteria. The analysis of the mutant forms revealed a delay at the catalytic dwell and associated decrease in Vmax, with magnitudes consistent with the level of disruption seen in the crystal structures. At least one of the mutant forms shows a previously un-observed dwell at the ATP binding angle, potentially attributable to slowed release of ADP. We discuss the correlation between crystal structures and single molecule results.
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Affiliation(s)
- Bradley C Steel
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU UK
| | - Ashley L Nord
- 1] Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU UK [2] Centre de Biochimie Structurale, 29 Rue de Navacelles, Montpellier, 34000, France
| | - Yamin Wang
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, The Chicago Medical School, North Chicago, Illinois, 60064, USA
| | - Vijayakanth Pagadala
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, The Chicago Medical School, North Chicago, Illinois, 60064, USA
| | - David M Mueller
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, The Chicago Medical School, North Chicago, Illinois, 60064, USA
| | - Richard M Berry
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU UK
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10
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Molecular determinants for nuclear import of influenza A PB2 by importin α isoforms 3 and 7. Structure 2015; 23:374-84. [PMID: 25599645 DOI: 10.1016/j.str.2014.11.015] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 11/14/2014] [Accepted: 11/18/2014] [Indexed: 11/23/2022]
Abstract
Influenza A virus polymerase subunit PB2 is a major virulence determinant implicated in pathogenicity and host adaptation. During cross-species virus transfer from avian to mammalian cells, PB2 switches specificity from importin α3 to α7. This specificity is not recapitulated in vitro, where PB2 binds all importin α isoforms with comparably high affinity. In this study, we investigated the structure, conformational dynamics, and autoinhibition of importin α isoforms 1, 3, and 7 in complex with PB2. Our data suggest that association of PB2 with α3 and α7 is favored by reduced autoinhibition of these isoforms and by the unique structure of the nuclear localization signal (NLS) domain of PB2. We propose that by recruiting importin α3 or α7 in the absence of importin β, PB2 reduces the complexity of adaptor-mediated import to a pseudo-bimolecular reaction, thereby acquiring a kinetic advantage over classical NLS cargos, which form an import complex only when importin α and β are simultaneously available.
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11
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Ahmad Z, Winjobi M, Kabir MA. Significance of αThr-349 in the catalytic sites of Escherichia coli ATP synthase. Biochemistry 2014; 53:7376-85. [PMID: 25375895 PMCID: PMC4255642 DOI: 10.1021/bi5013063] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
![]()
This
paper describes the role of α-subunit VISIT-DG sequence
residue αThr-349 in the catalytic sites of Escherichia
coli F1Fo ATP synthase. X-ray structures
show the highly conserved αThr-349 in the proximity (2.68 Å)
of the conserved phosphate binding residue βR182 in the phosphate
binding subdomain. αT349A, -D, -Q, and -R mutations caused 90–100-fold
losses of oxidative phosphorylation and reduced ATPase activity of
F1Fo in membranes. Double mutation αT349R/βR182A
was able to partially compensate for the absence of known phosphate
binding residue βR182. Azide, fluoroaluminate, and fluoroscandium
caused insignificant inhibition of αT349A, -D, and -Q mutants,
slight inhibition of the αT349R mutant, partial inhibition of
the αT349R/βR182A double mutant, and complete inhibition
of the wild type. Whereas NBD-Cl (7-chloro-4-nitrobenzo-2-oxa-1,3-diazole)
inhibited wild-type ATPase and its αT349A, -D, -R, and -Q mutants
essentially completely, βR182A ATPase and double mutant αT349A/βR182A
were inhibited partially. Inhibition characteristics supported the
conclusion that NBD-Cl reacts in βE (empty) catalytic sites,
as shown previously by X-ray structure analysis. Phosphate protected
against NBD-Cl inhibition in the wild type, αT349R, and double
mutant αT349R/βR182A but not in αT349A, αT349D,
or αT349Q. The results demonstrate that αThr-349 is a
supplementary residue involved in phosphate binding and transition
state stabilization in ATP synthase catalytic sites through its interaction
with βR182.
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Affiliation(s)
- Zulfiqar Ahmad
- Department of Biochemistry, Kirksville College of Osteopathic Medicine, A. T. Still University of Health Sciences , Kirksville, Missouri 63501, United States
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Bockenhauer SD, Duncan TM, Moerner WE, Börsch M. The regulatory switch of F 1-ATPase studied by single-molecule FRET in the ABEL Trap. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2014; 8950:89500H. [PMID: 25309100 DOI: 10.1117/12.2042688] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
F1-ATPase is the soluble portion of the membrane-embedded enzyme FoF1-ATP synthase that catalyzes the production of adenosine triphosphate in eukaryotic and eubacterial cells. In reverse, the F1 part can also hydrolyze ATP quickly at three catalytic binding sites. Therefore, catalysis of 'non-productive' ATP hydrolysis by F1 (or FoF1) must be minimized in the cell. In bacteria, the ε subunit is thought to control and block ATP hydrolysis by mechanically inserting its C-terminus into the rotary motor region of F1. We investigate this proposed mechanism by labeling F1 specifically with two fluorophores to monitor the C-terminus of the ε subunit by Förster resonance energy transfer. Single F1 molecules are trapped in solution by an Anti-Brownian electrokinetic trap which keeps the FRET-labeled F1 in place for extended observation times of several hundreds of milliseconds, limited by photobleaching. FRET changes in single F1 and FRET histograms for different biochemical conditions are compared to evaluate the proposed regulatory mechanism.
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Affiliation(s)
- Samuel D Bockenhauer
- Department of Chemistry, Stanford University, Stanford, CA, USA ; Department of Physics, Stanford University, Stanford, CA, USA
| | - Thomas M Duncan
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - W E Moerner
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Michael Börsch
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany
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Duncan TM, Düser MG, Heitkamp T, McMillan DGG, Börsch M. Regulatory conformational changes of the ε subunit in single FRET-labeled F oF 1-ATP synthase. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2014; 8948:89481J. [PMID: 25076824 DOI: 10.1117/12.2040463] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Subunit ε is an intrinsic regulator of the bacterial FoF1-ATP synthase, the ubiquitous membrane-embedded enzyme that utilizes a proton motive force in most organisms to synthesize adenosine triphosphate (ATP). The C-terminal domain of ε can extend into the central cavity formed by the α and β subunits, as revealed by the recent X-ray structure of the F1 portion of the Escherichia coli enzyme. This insertion blocks the rotation of the central γ subunit and, thereby, prevents wasteful ATP hydrolysis. Here we aim to develop an experimental system that can reveal conditions under which ε inhibits the holoenzyme FoF1-ATP synthase in vitro. Labeling the C-terminal domain of ε and the γ subunit specifically with two different fluorophores for single-molecule Förster resonance energy transfer (smFRET) allowed monitoring of the conformation of ε in the reconstituted enzyme in real time. New mutants were made for future three-color smFRET experiments to unravel the details of regulatory conformational changes in ε.
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Affiliation(s)
- Thomas M Duncan
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Monika G Düser
- 3 Institute of Physics, Stuttgart University, Stuttgart, Germany
| | - Thomas Heitkamp
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Duncan G G McMillan
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Michael Börsch
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany
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