Tuning the photoexcitation response of cyanobacterial Photosystem I via reconstitution into Proteoliposomes

Abstract

The role of natural thylakoid membrane housing of Photosystem I (PSI), the transmembrane photosynthetic protein, in its robust photoactivated charge separation with near unity quantum efficiency is not fundamentally understood. To this end, incorporation of suitable protein scaffolds for PSI incorporation is of great scientific and device manufacturing interest. Areas of interest include solid state bioelectronics, and photoelectrochemical devices that require bio-abio interfaces that do not compromise the photoactivity and photostability of PSI. Therefore, the surfactant-induced membrane solubilization of a negatively charged phospholipid (DPhPG) with the motivation of creating biomimetic reconstructs of PSI reconstitution in DPhPG liposomes is studied. Specifically, a simple yet elegant method for incorporation of PSI trimeric complexes into DPhPG bilayer membranes that mimic the natural thylakoid membrane housing of PSI is introduced. The efficacy of this method is demonstrated via absorption and fluorescence spectroscopy measurements as well as direct visualization using atomic force microscopy. This study provides direct evidence that PSI confinements in synthetic lipid scaffolds can be used for tuning the photoexcitation characteristics of PSI. Hence, it paves the way for development of fundamental understanding of microenvironment alterations on photochemical response of light activated membrane proteins.

Jolly green MOF: confinement and photoactivation of photosystem I in a metal–organic framework

“…Interestingly, this is also in agreement with the previously reported connement effects in PSI-proteoliposomes. 67 However, what creates the confusion in attributing this distinctive shi to the connement effects is that this emission prole appears uncannily similar to that of the uncoupled chlorophyll (i.e., when PSI is denatured by 2% SDS as seen in Fig. 6b or by 75% ethanol as seen in Fig.…”

Tuning the photocurrent generations from photosystem I assembled in tailored biotic-abiotic interfaces

“…Details regarding the PSI reconstitution using TX-100 can be found in our previous study. [12,13] For PSI reconstitution using DDM, the solution was equilibrated for 24 h, then mixed with the solubilized protein in 200 mM Na phosphate buffer (pH 7.0), and afterwards, the mixture was incubated for 30 min at room temperature under gentle agitation. The final [protein-to-lipid weight ratios (wPLR)] used for all our studies were 1.2.…”

“…Details of alkanethiolate SAM/Au substrates preparations are provided in our previous work [12] where monolayers of C 4 -COOH, C 4 -OH, and C 6 -OH were formed on Au substrates by immersing the substrates in 5 mM ethanolic solution of 4-mercaptobutyric acid (HS-C 3 H 6 -COOH, Sigma-Aldrich), 4-mercapto-1-butanol (HS-C 4 H 8 -OH, Sigma-Aldrich), and 6-mercapto-1-hexanol (HS-C 6 H 12 -OH, Sigma-Aldrich), respectively. Thereafter, 150 µl of protein-lipid suspensions were drop casted on the alkanethiolate SAM/Au substrates and incubated for 1 h at 45°C.…”

“…Firstly, to understand how microenvironment confinements regulate the inter-chromophore electronic coupling within the PSI complex, a high-density encapsulation of PSI in synthetic lipid bilayer membranes via detergent-mediated reconstitution will be considered. [12,13] To this end, the PSI-proteoliposomes were immobilized onto bio-hybrid electrodes and the PEC response of the system was subsequently characterized. In particular, detailed photocurrent investigations of specific alkanethiolate SAM ()/Au surfaces decorated with PSI encapsulated in DPhPG [1,2-diphytanoyl-sn-glycero-3-phospho-(1 ′ -rac-glycerol)] liposomes will be presented here.…”

A new platform for development of photosystem I based thin films with superior photocurrent: TCNQ charge transfer salts derived from ZIF-8

“…To this end, our recent studies have shown considerable alterations in the photochemical and optical responses along with signicant photocurrent enhancements due to the lipid bilayer mediated PSI microenvironment alterations. 28,30,31 Thus, whether by introducing more favorable redox steps, greater functional surface area, or more complete conduction pathways, such efforts have continuously pushed the frontiers of biohybrid photovoltaics or photochemical energy conversion routes.…”