Active transport of Ca2+ by an artificial photosynthetic membrane

Ira M. Bennett, Hebe M. Vanegas Farfano, Federica Bogani, Alex Primak, Paul A. Liddell, Luis Otero, Leonides Sereno, Juana J. Silber, Ana L Moore, Thomas A Moore, John Devens Gust

Research output: Contribution to journalArticle

97 Citations (Scopus)

Abstract

Transport of calcium ions across membranes and against a thermodynamic gradient is essential to many biological processes, including muscle contraction, the citric acid cycle, glycogen metabolism, release of neurotransmitters, vision, biological signal transduction and immune response. Synthetic systems that transport metal ions across lipid or liquid membranes are well known, and in some cases light has been used to facilitate transport. Typically, a carrier molecule located in a symmetric membrane binds the ion from aqueous solution on one side and releases it on the other. The thermodynamic driving force is provided by an ion concentration difference between the two aqueous solutions, coupling to such a gradient in an auxiliary species, or photomodulation of the carrier by an asymmetric photon flux. Here we report a different approach, in which active transport is driven not by concentration gradients, but by light-induced electron transfer in a photoactive molecule that is asymmetrically disposed across a lipid bilayer. The system comprises a synthetic, light-driven transmembrane Ca2+ pump based on a redox-sensitive, lipophilic Ca2+-binding shuttle molecule whose function is powered by an intramembrane artificial photosynthetic reaction centre. The resulting structure transports calcium ions across the bilayer of a liposome to develop both a calcium ion concentration gradient and a membrane potential, expanding Mitchell's concept of a redox loop mechanism for protons to include divalent cations. Although the quantum yield is relatively low (∼1 per cent), the Ca2+ electrochemical potential developed is significant.

Original languageEnglish
Pages (from-to)398-401
Number of pages4
JournalNature
Volume420
Issue number6914
DOIs
Publication statusPublished - Nov 28 2002

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Artificial Membranes
Active Biological Transport
Ion Transport
Ions
Calcium
Thermodynamics
Light
Oxidation-Reduction
Membranes
Photosynthetic Reaction Center Complex Proteins
Biological Phenomena
Citric Acid Cycle
Divalent Cations
Lipid Bilayers
Muscle Contraction
Glycogen
Photons
Liposomes
Membrane Potentials
Neurotransmitter Agents

ASJC Scopus subject areas

  • General

Cite this

Bennett, I. M., Vanegas Farfano, H. M., Bogani, F., Primak, A., Liddell, P. A., Otero, L., ... Gust, J. D. (2002). Active transport of Ca2+ by an artificial photosynthetic membrane. Nature, 420(6914), 398-401. https://doi.org/10.1038/nature01209

Active transport of Ca2+ by an artificial photosynthetic membrane. / Bennett, Ira M.; Vanegas Farfano, Hebe M.; Bogani, Federica; Primak, Alex; Liddell, Paul A.; Otero, Luis; Sereno, Leonides; Silber, Juana J.; Moore, Ana L; Moore, Thomas A; Gust, John Devens.

In: Nature, Vol. 420, No. 6914, 28.11.2002, p. 398-401.

Research output: Contribution to journalArticle

Bennett, IM, Vanegas Farfano, HM, Bogani, F, Primak, A, Liddell, PA, Otero, L, Sereno, L, Silber, JJ, Moore, AL, Moore, TA & Gust, JD 2002, 'Active transport of Ca2+ by an artificial photosynthetic membrane', Nature, vol. 420, no. 6914, pp. 398-401. https://doi.org/10.1038/nature01209
Bennett IM, Vanegas Farfano HM, Bogani F, Primak A, Liddell PA, Otero L et al. Active transport of Ca2+ by an artificial photosynthetic membrane. Nature. 2002 Nov 28;420(6914):398-401. https://doi.org/10.1038/nature01209
Bennett, Ira M. ; Vanegas Farfano, Hebe M. ; Bogani, Federica ; Primak, Alex ; Liddell, Paul A. ; Otero, Luis ; Sereno, Leonides ; Silber, Juana J. ; Moore, Ana L ; Moore, Thomas A ; Gust, John Devens. / Active transport of Ca2+ by an artificial photosynthetic membrane. In: Nature. 2002 ; Vol. 420, No. 6914. pp. 398-401.
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