Extension of the spectral range of bacteriorhodopsin functional activity by energy transfer from quantum dots

Monodispersed semiconductor nanocrystals or quantum dots (QDs) specifically immobilized on the surface of purple membranes (PMs) containing bacteriorhodopsin (bR) can harvest light in the UV to blue region, which cannot be absorbed efficiently by the PMs alone, and transfer the harvested energy to the retinal chromophores of bR via highly efficient Förster resonance energy transfer (FRET). CdTe or CdSe/ZnS QDs with a quantum yield as high as 70% have been used to estimate different parameters characterizing the improvement of the bR biological function caused by nanocrystals. AFM examination has shown that the most FRET-efficient QD–PM hybrid structures are characterized by the highest level of QD ordering; hence, AFM imaging of bR–PM hybrid materials provides the basis for optimization of the assembly design in order to engineer bio-hybrid structures with advanced optical and photovoltaic properties. Oriented bR-containing proteoliposomes tagged with QDs at a QD-to-bR molar ratio of up to 1:5 have been engineered and used to analyze the photoresponse, with the bR proton pumping considerably increased. Finally, the kinetics of the potential/current generation in films of oriented bR containing or not containing QDs have been analyzed. Incorporation of QDs resulted in an increase in the potential/current generation rate and in an almost fourfold increase in the rate of Mform formation. Thus, the improvement of the bR native function by QDs may be caused by two reasons: an extension of the range of utilized light and an increase in the rate of the bR photocycle.

[1]  Shigeki Mitaku,et al.  Reconstitution of Bacteriorhodopsin into Cyclic Lipid Vesicles , 2008, Bioscience, biotechnology, and biochemistry.

[2]  D. Birnbaum,et al.  A HIGHLY REACTIVE HETEROATOM ANALOG OF RETINAL AND ITS INTERACTION WITH BACTERIORHODOPSIN , 1984 .

[3]  D. Oesterhelt,et al.  Functions of a new photoreceptor membrane. , 1973, Proceedings of the National Academy of Sciences of the United States of America.

[4]  Albert F. Lawrence,et al.  Biomolecular Electronics: Protein-Based Associative Processors and Volumetric Memories , 1999 .

[5]  Igor Nabiev,et al.  Nanocrystal-encoded fluorescent microbeads for proteomics: antibody profiling and diagnostics of autoimmune diseases. , 2007, Nano letters.

[6]  K Dane Wittrup,et al.  Monovalent, reduced-size quantum dots for imaging receptors on living cells , 2008, Nature Methods.

[7]  A. Watts,et al.  The essential role of specific Halobacterium halobium polar lipids in 2D-array formation of bacteriorhodopsin. , 1992, Biochimica et biophysica acta.

[8]  G. Chumanov,et al.  The chromophore-binding site of bacteriorhodopsin. Resonance Raman and surface-enhanced resonance Raman spectroscopy and quantum chemical study , 1985, Journal of Biosciences.

[9]  Igor Nabiev,et al.  Probing cell-type-specific intracellular nanoscale barriers using size-tuned quantum dots. , 2009, Small.

[10]  Christopher B. Murray,et al.  Synthesis and Characterization of Monodisperse Nanocrystals and Close-Packed Nanocrystal Assemblies , 2000 .

[11]  Thomas A. Klar,et al.  Aqueous synthesis of thiol-capped CdTe nanocrystals : State-of-the-art , 2007 .

[12]  D. Oesterhelt,et al.  Isolation of the cell membrane of Halobacterium halobium and its fractionation into red and purple membrane. , 1974, Methods in enzymology.

[13]  Igor Nabiev,et al.  Fluorescent Colloidal Particles as Detection Tools in Biotechnology Systems , 2007 .

[14]  W. Stoeckenius,et al.  Reconstitution of purple membrane vesicles catalyzing light-driven proton uptake and adenosine triphosphate formation. , 1974, The Journal of biological chemistry.

[15]  Igor Nabiev,et al.  Resonance energy transfer improves the biological function of bacteriorhodopsin within a hybrid material built from purple membranes and semiconductor quantum dots. , 2010, Nano letters.

[16]  R. Nitschke,et al.  Quantum dots versus organic dyes as fluorescent labels , 2008, Nature Methods.

[17]  Nikolai Vsevolodov,et al.  Biomolecular Electronics: An Introduction via Photosensitive Proteins , 1998 .

[18]  Steven G. Boxer,et al.  Re‐engineering photosynthetic reaction centers , 2008 .

[19]  D. Oesterhelt,et al.  The structure and mechanism of the family of retinal proteins from halophilic archaea. , 1998, Current opinion in structural biology.

[20]  Ida Lee,et al.  Biomolecular Electronics: Vectorial Arrays of Photosynthetic Reaction Centers , 1997 .

[21]  M. Krebs,et al.  Ordered membrane insertion of an archaeal opsin in vivo. , 2000, Proceedings of the National Academy of Sciences of the United States of America.