A c Subunit with Four Transmembrane Helices and One Ion (Na+)-binding Site in an Archaeal ATP Synthase

Mayer, Florian; Leone, Vanessa; Langer, Julian D.; Faraldo‐Gómez, José D.; Müller, Volker

doi:10.1074/jbc.m112.411223

Cited by 23 publications

(37 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The determination of the selectivity of the I. tartaricus c-ring has enabled us to challenge a previously proposed theoretical framework, based on MD simulations, with which we have compared and rationalized the functional specificity of different rotary ATPases (17,29,30,33). The quantitative agreement between computational and experimental results obtained here validates that approach and therefore substantiates the principle of ion selectivity derived from it.…”

Section: Discussionsupporting

confidence: 66%

“…As mentioned in the Introduction, previous theoretical studies based on of a range of experimental structures and computergenerated models have led us to formulate the structural basis for the principle of ion selectivity of the rotor ring, and enabled us to rationalize the strikingly broad spectrum of selectivity values that seem to occur in nature, which spans a least 10 orders of magnitude (17,29,30). The rotor rings of E. hirae and I. tartaricus are on the same end of that broad spectrum, but the difference in their ion selectivity is nevertheless significant.…”

Section: Resultsmentioning

confidence: 99%

“…ATP synthases in the middle of this spectrum, such as that in Methanosarcina acetivorans, are concurrently coupled to H + and Na + , as both ion types compete in physiological conditions for the multiple (and identical) binding sites in the ring (17). At the structural level, we have proposed that the inherent H + selectivity of all rotor rings is conferred by the strictly conserved carboxylate side chain in their ion-binding sites, and that this inherent H + selectivity is gradually weakened or enhanced through localized structural and chemical adaptations (17,29,30). Specifically, in enzymes coupled to Na + , the H + selectivity of the key carboxyl side chain is countered by the presence of multiple polar groups able to coordinate a Na + ion, whereas in H + -coupled c-rings the opposite is accomplished through hydrophobic substitutions.…”

Section: Discussionmentioning

confidence: 99%

“…In previous theoretical studies, we have addressed this question for the family of ion-motive ATPases (17,29,30), which comprises eukaryotic and prokaryotic ATP synthases, as well as vacuolar ion pumps. In these multicomponent enzymes, a membrane-embedded substructure known as the rotor ring can revolve around its axis, relative to the rest of the protein's membrane domain.…”

Section: Significancementioning

confidence: 99%

See 3 more Smart Citations

On the principle of ion selectivity in Na ⁺ /H ⁺ -coupled membrane proteins: Experimental and theoretical studies of an ATP synthase rotor

Leone

Pogoryelov

Meier

et al. 2015

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

Self Cite

View full text Add to dashboard Cite

Numerous membrane transporters and enzymes couple their mechanisms to the permeation of Na + or H + , thereby harnessing the energy stored in the form of transmembrane electrochemical potential gradients to sustain their activities. The molecular and environmental factors that control and modulate the ion specificity of most of these systems are, however, poorly understood. Here, we use isothermal titration calorimetry to determine the Na + /H + selectivity of the ion-driven membrane rotor of an F-type ATP synthase. Consistent with earlier theoretical predictions, we find that this rotor is significantly H + selective, although not sufficiently to be functionally coupled to H + , owing to the large excess of Na + in physiological settings. The functional Na + specificity of this ATP synthase thus results from two opposing factors, namely its inherent chemical selectivity and the relative availability of the coupling ion. Further theoretical studies of this membrane rotor, and of two others with a much stronger and a slightly weaker H + selectivity, indicate that, although the inherent selectivity of their ion-binding sites is largely set by the balance of polar and hydrophobic groups flanking a conserved carboxylic side chain, subtle variations in their structure and conformational dynamics, for a similar chemical makeup, can also have a significant contribution. We propose that the principle of ion selectivity outlined here may provide a rationale for the differentiation of Na + -and H + -coupled systems in other families of membrane transporters and enzymes. molecular motor | ion-coupled transport | binding thermodynamics | energy transduction | membrane bioenergetics G radients in the electrochemical potential of H + or Na + across biological membranes sustain a wide range of essential cellular process. The resulting proton or sodium motive forces (pmf, smf) are the predominant energy source for secondary-active membrane transporters, which mediate the uptake of many substances required by the cell (1-3), and also enable pathogenic bacteria to protect themselves from human-made antibiotics and other toxic compounds (4-6). Downhill membrane permeation of Na + and H + across the membrane also powers the ATP synthase (7), which produces most of cellular ATP, and energizes the rotation of bacterial flagella (8). Thus, the importance of this mode of energy transduction in cells cannot be overstated. Nevertheless, little is known about the factors that control and modulate the specificity for Na + or H + in most of these processes.It seems clear, although, that there is no correlation between function type and ion specificity; that is, the same process in different species can be coupled to either Na + or H + (2, 5-7, 9-11). Organism-specific environmental factors, such as temperature or pH, also do not provide a consistent rationale; for example, ATP synthases from thermoalkaliphilic bacteria use a H + gradient despite the scarcity of H + and the potentially greater degree of H + leakage across the membrane at hig...

show abstract

Section: Discussionsupporting

confidence: 66%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Significancementioning

confidence: 99%

See 2 more Smart Citations

On the principle of ion selectivity in Na ⁺ /H ⁺ -coupled membrane proteins: Experimental and theoretical studies of an ATP synthase rotor

Leone

Pogoryelov

Meier

et al. 2015

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

Self Cite

View full text Add to dashboard Cite

show abstract

“…Most interestingly, the gene encoding the rotor subunit c (ELI_2186) is 474 bp long and encodes a 15.72-kDa protein with four transmembrane helices (TMH). Like the c subunits from the F 1 F o ATP synthase from A. woodii (32) or the A 1 A o ATP synthase from Pyrococcus furiosus (33), it contains a conserved Na ϩ binding motif (Q. . .ET) but only one ion-binding site.…”

Section: Resultsmentioning

confidence: 99%

Energy Conservation Model Based on Genomic and Experimental Analyses of a Carbon Monoxide-Utilizing, Butyrate-Forming Acetogen, Eubacterium limosum KIST612

Jeong

Bertsch

Hess

et al. 2015

Appl Environ Microbiol

Self Cite

View full text Add to dashboard Cite

c Eubacterium limosum KIST612 is one of the few acetogens that can produce butyrate from carbon monoxide. We have used a genome-guided analysis to delineate the path of butyrate formation, the enzymes involved, and the potential coupling to ATP synthesis. Oxidation of CO is catalyzed by the acetyl-coenzyme A (CoA) synthase/CO dehydrogenase and coupled to the reduction of ferredoxin. Oxidation of reduced ferredoxin is catalyzed by the Rnf complex and Na ؉ dependent. Consistent with the finding of a Na ؉ -dependent Rnf complex is the presence of a conserved Na ؉ -binding motif in the c subunit of the ATP synthase. Butyrate formation is from acetyl-CoA via acetoacetyl-CoA, hydroxybutyryl-CoA, crotonyl-CoA, and butyryl-CoA and is consistent with the finding of a gene cluster that encodes the enzymes for this pathway. The activity of the butyryl-CoA dehydrogenase was demonstrated. Reduction of crotonyl-CoA to butyryl-CoA with NADH as the reductant was coupled to reduction of ferredoxin. We postulate that the butyryl-CoA dehydrogenase uses flavin-based electron bifurcation to reduce ferredoxin, which is consistent with the finding of etfA and etfB genes next to it. The overall ATP yield was calculated and is significantly higher than the one obtained with H 2 ؉ CO 2 . The energetic benefit may be one reason that butyrate is formed only from CO but not from H 2 ؉ CO 2 .A cetogenic bacteria are a phylogenetically diverse group of strictly anaerobic bacteria able to reduce two molecules of CO 2 to acetate by the Wood-Ljungdahl pathway (WLP) (1-4). Electrons may derive from molecular hydrogen (autotrophic growth), from carbon monoxide, or from organic donors (heterotrophic growth) such as hexoses, pentoses, formate, lactate, alcohols, or methyl group donors (1). Not only does the WLP provide the cell with organic material for biomass formation, but it is also coupled to energy conservation for ATP supply by a chemiosmotic mechanism (2, 5). Every acetogen examined to date uses reduced ferredoxin (Fd) as the electron donor for an ion-translocating membrane protein complex, and acetogens can have either an Fd:NAD ϩ oxidoreductase (Rnf) or an Fd:H ϩ oxidoreductase (Ech) complex for generation of an ion motive force (5). In both cases, the ion gradient can be either an H ϩ or an Na ϩ gradient. The electrochemical ion gradient thus established is then used by a membrane bound, H ϩ -or Na ϩ -translocating F 1 F o ATP synthase (2).Acetate production from CO 2 proceeds via formate that is converted to formyl-tetrahydrofolate (THF) in an ATP-consuming reaction (6). Water is split off from formyl-THF to yield methenyl-THF, which is reduced via methylene-THF to methyl-THF. The latter is condensed with CO (derived from another molecule of CO 2 ) and coenzyme A (CoA) to acetyl-CoA, which is the starting molecule for biosynthetic reactions (4,7,8). Acetyl-CoA is also the precursor of the end product, acetate, that is produced by the enzymes acetyltransferase and acetate kinase. ATP production in the acetate kinase reaction is of special...

show abstract

ATP synthases from archaea: The beauty of a molecular motor

Grüber

Manimekalai

Mayer

et al. 2014

Biochimica et Biophysica Acta (BBA) - Bioenergetics

109

108

View full text Add to dashboard Cite

Archaea live under different environmental conditions, such as high salinity, extreme pHs and cold or hot temperatures. How energy is conserved under such harsh environmental conditions is a major question in cellular bioenergetics of archaea. The key enzymes in energy conservation are the archaeal A1AO ATP synthases, a class of ATP synthases distinct from the F1FO ATP synthase ATP synthase found in bacteria, mitochondria and chloroplasts and the V1VO ATPases of eukaryotes. A1AO ATP synthases have distinct structural features such as a collar-like structure, an extended central stalk, and two peripheral stalks possibly stabilizing the A1AO ATP synthase during rotation in ATP synthesis/hydrolysis at high temperatures as well as to provide the storage of transient elastic energy during ion-pumping and ATP synthesis/-hydrolysis. High resolution structures of individual subunits and subcomplexes have been obtained in recent years that shed new light on the function and mechanism of this unique class of ATP synthases. An outstanding feature of archaeal A1AO ATP synthases is their diversity in size of rotor subunits and the coupling ion used for ATP synthesis with H(+), Na(+) or even H(+) and Na(+) using enzymes. The evolution of the H(+) binding site to a Na(+) binding site and its implications for the energy metabolism and physiology of the cell are discussed.

show abstract

A c Subunit with Four Transmembrane Helices and One Ion (Na+)-binding Site in an Archaeal ATP Synthase

Abstract: Background:The ATP synthase of Pyrococcus has an unusual gene encoding rotor subunit c. Results: The c ring is made of protomers with one ion-binding site in four transmembrane helices and is highly Na ϩ -specific.

Cited by 23 publications

References 65 publications

On the principle of ion selectivity in Na ⁺ /H ⁺ -coupled membrane proteins: Experimental and theoretical studies of an ATP synthase rotor

On the principle of ion selectivity in Na ⁺ /H ⁺ -coupled membrane proteins: Experimental and theoretical studies of an ATP synthase rotor

Energy Conservation Model Based on Genomic and Experimental Analyses of a Carbon Monoxide-Utilizing, Butyrate-Forming Acetogen, Eubacterium limosum KIST612

ATP synthases from archaea: The beauty of a molecular motor

Contact Info

Product

Resources

About

A c Subunit with Four Transmembrane Helices and One Ion (Na+)-binding Site in an Archaeal ATP Synthase

Abstract: Background:The ATP synthase of Pyrococcus has an unusual gene encoding rotor subunit c. Results: The c ring is made of protomers with one ion-binding site in four transmembrane helices and is highly Na ϩ -specific.

Cited by 23 publications

References 65 publications

On the principle of ion selectivity in Na + /H + -coupled membrane proteins: Experimental and theoretical studies of an ATP synthase rotor

On the principle of ion selectivity in Na + /H + -coupled membrane proteins: Experimental and theoretical studies of an ATP synthase rotor

Energy Conservation Model Based on Genomic and Experimental Analyses of a Carbon Monoxide-Utilizing, Butyrate-Forming Acetogen, Eubacterium limosum KIST612

ATP synthases from archaea: The beauty of a molecular motor

Contact Info

Product

Resources

About

On the principle of ion selectivity in Na ⁺ /H ⁺ -coupled membrane proteins: Experimental and theoretical studies of an ATP synthase rotor

On the principle of ion selectivity in Na ⁺ /H ⁺ -coupled membrane proteins: Experimental and theoretical studies of an ATP synthase rotor