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Galkin MA, Russell AN, Vik SB, Berry RM, Ishmukhametov RR. Detergent-free Ultrafast Reconstitution of Membrane Proteins into Lipid Bilayers Using Fusogenic Complementary-charged Proteoliposomes. J Vis Exp 2018. [PMID: 29683454 PMCID: PMC5933413 DOI: 10.3791/56909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Detergents are indispensable for delivery of membrane proteins into 30-100 nm small unilamellar vesicles, while more complex, larger model lipid bilayers are less compatible with detergents. Here we describe a strategy for bypassing this fundamental limitation using fusogenic oppositely charged liposomes bearing a membrane protein of interest. Fusion between such vesicles occurs within 5 min in a low ionic strength buffer. Positively charged fusogenic liposomes can be used as simple shuttle vectors for detergent-free delivery of membrane proteins into biomimetic target lipid bilayers, which are negatively charged. We also show how to reconstitute membrane proteins into fusogenic proteoliposomes with a fast 30-min protocol. Combining these two approaches, we demonstrate a fast assembly of an electron transport chain consisting of two membrane proteins from E. coli, a primary proton pump bo3-oxidase and F1Fo ATP synthase, in membranes of vesicles of various sizes, ranging from 0.1 to >10 microns, as well as ATP production by this chain.
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Affiliation(s)
| | - Aidan N Russell
- Clarendon Laboratory, Department of Physics, Oxford University
| | - Steven B Vik
- Department of Biological Sciences, Southern Methodist University
| | - Richard M Berry
- Clarendon Laboratory, Department of Physics, Oxford University
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Analysis of an N-terminal deletion in subunit a of the Escherichia coli ATP synthase. J Bioenerg Biomembr 2017; 49:171-181. [PMID: 28078625 DOI: 10.1007/s10863-017-9694-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 01/04/2017] [Indexed: 10/20/2022]
Abstract
Subunit a is a membrane-bound stator subunit of the ATP synthase and is essential for proton translocation. The N-terminus of subunit a in E. coli is localized to the periplasm, and contains a sequence motif that is conserved among some bacteria. Previous work has identified mutations in this region that impair enzyme activity. Here, an internal deletion was constructed in subunit a in which residues 6-20 were replaced by a single lysine residue, and this mutant was unable to grow on succinate minimal medium. Membrane vesicles prepared from this mutant lacked ATP synthesis and ATP-driven proton translocation, even though immunoblots showed a significant level of subunit a. Similar results were obtained after purification and reconstitution of the mutant ATP synthase into liposomes. The location of subunit a with respect to its neighboring subunits b and c was probed by introducing cysteine substitutions that were known to promote cross-linking: a_L207C + c_I55C, a_L121C + b_N4C, and a_T107C + b_V18C. The last pair was unable to form cross-links in the background of the deletion mutant. The results indicate that loss of the N-terminal region of subunit a does not generally disrupt its structure, but does alter interactions with subunit b.
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Abstract
The F1F0-ATP synthase (EC 3.6.1.34) is a remarkable enzyme that functions as a rotary motor. It is found in the inner membranes of Escherichia coli and is responsible for the synthesis of ATP in response to an electrochemical proton gradient. Under some conditions, the enzyme functions reversibly and uses the energy of ATP hydrolysis to generate the gradient. The ATP synthase is composed of eight different polypeptide subunits in a stoichiometry of α3β3γδεab2c10. Traditionally they were divided into two physically separable units: an F1 that catalyzes ATP hydrolysis (α3β3γδε) and a membrane-bound F0 sector that transports protons (ab2c10). In terms of rotary function, the subunits can be divided into rotor subunits (γεc10) and stator subunits (α3β3δab2). The stator subunits include six nucleotide binding sites, three catalytic and three noncatalytic, formed primarily by the β and α subunits, respectively. The stator also includes a peripheral stalk composed of δ and b subunits, and part of the proton channel in subunit a. Among the rotor subunits, the c subunits form a ring in the membrane, and interact with subunit a to form the proton channel. Subunits γ and ε bind to the c-ring subunits, and also communicate with the catalytic sites through interactions with α and β subunits. The eight subunits are expressed from a single operon, and posttranscriptional processing and translational regulation ensure that the polypeptides are made at the proper stoichiometry. Recent studies, including those of other species, have elucidated many structural and rotary properties of this enzyme.
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Sugimoto Y, Konoki K, Murata M, Matsushita M, Kanazawa H, Oishi T. Design, Synthesis, and Biological Evaluation of Fluorinated Analogues of Salicylihalamide. J Med Chem 2008; 52:798-806. [DOI: 10.1021/jm801265e] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yoshinori Sugimoto
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Keiichi Konoki
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Masafumi Matsushita
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Hiroshi Kanazawa
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Tohru Oishi
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
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York J, Spetzler D, Hornung T, Ishmukhametov R, Martin J, Frasch WD. Abundance of Escherichia coli F1-ATPase molecules observed to rotate via single-molecule microscopy with gold nanorod probes. J Bioenerg Biomembr 2007; 39:435-9. [DOI: 10.1007/s10863-007-9114-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ishmukhametov RR, Pond JB, Al-Huqail A, Galkin MA, Vik SB. ATP synthesis without R210 of subunit a in the Escherichia coli ATP synthase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1777:32-8. [PMID: 18068111 DOI: 10.1016/j.bbabio.2007.11.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 11/02/2007] [Accepted: 11/07/2007] [Indexed: 11/29/2022]
Abstract
Interactions between subunit a and oligomeric subunit c are essential for the coupling of proton translocation to rotary motion in the ATP synthase. A pair of previously described mutants, R210Q/Q252R and P204T/R210Q/Q252R [L.P. Hatch, G.B. Cox and S.M. Howitt, The essential arginine residue at position 210 in the a subunit of the Escherichia coli ATP synthase can be transferred to position 252 with partial retention of activity, J. Biol. Chem. 270 (1995) 29407-29412] has been constructed and further analyzed. These mutants, in which the essential arginine of subunit a, R210, was switched with a conserved glutamine residue, Q252, are shown here to be capable of both ATP synthesis by oxidative phosphorylation, and ATP-driven proton translocation. In addition, lysine can replace the arginine at position 252 with partial retention of both activities. The pH dependence of ATP-driven proton translocation was determined after purification of mutant enzymes, and reconstitution into liposomes. Proton translocation by the lysine mutant, and to a lesser extent the arginine mutant, dropped off sharply above pH 7.5, consistent with the requirement for a positive charge during function. Finally, the rates of ATP synthesis and of ATP-driven proton translocation were completely inhibited by treatment with DCCD (N,N'-dicyclohexylcarbodiimide), while rates of ATP hydrolysis by the mutants were not significantly affected, indicating that DCCD modification disrupts the F(1)-F(o) interface. The results suggest that minimal requirements for proton translocation by the ATP synthase include a positive charge in subunit a and a weak interface between subunit a and oligomeric subunit c.
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Affiliation(s)
- Robert R Ishmukhametov
- Department of Biological Sciences, Box 750376, Southern Methodist University, Dallas, TX 75275-0376, USA
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Claggett SB, Grabar TB, Dunn SD, Cain BD. Functional incorporation of chimeric b subunits into F1Fo ATP synthase. J Bacteriol 2007; 189:5463-71. [PMID: 17526709 PMCID: PMC1951835 DOI: 10.1128/jb.00191-07] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
F(1)F(o) ATP synthases function by a rotary mechanism. The enzyme's peripheral stalk serves as the stator that holds the F(1) sector and its catalytic sites against the movement of the rotor. In Escherichia coli, the peripheral stalk is a homodimer of identical b subunits, but photosynthetic bacteria have open reading frames for two different b-like subunits thought to form heterodimeric b/b' peripheral stalks. Chimeric b subunit genes have been constructed by substituting sequence from the Thermosynechococcus elongatus b and b' genes in the E. coli uncF gene, encoding the b subunit. The recombinant genes were expressed alone and in combination in the E. coli deletion strain KM2 (Deltab). Although not all of the chimeric subunits were incorporated into F(1)F(o) ATP synthase complexes, plasmids expressing either chimeric b(E39-I86) or b'(E39-I86) were capable of functionally complementing strain KM2 (Deltab). Strains expressing these subunits grew better than cells with smaller chimeric segments, such as those expressing the b'(E39-D53) or b(L54-I86) subunit, indicating intragenic suppression. In general, the chimeric subunits modeled on the T. elongatus b subunit proved to be more stable than the b' subunit in vitro. Coexpression of the b(E39-I86) and b'(E39-I86) subunits in strain KM2 (Deltab) yielded F(1)F(o) complexes containing heterodimeric peripheral stalks composed of both subunits.
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Affiliation(s)
- Shane B Claggett
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32605, USA
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