Proteorhodopsine - Recombinantly expressed in E.coli inner plasma membrane
SURFE2R N1 data and applications:
Light stimuli of 50 ms have been repeated each 500 ms to observe transient currents in Proteorhodopsin. Current signals were compared across different samples: Purified inner E.coli membranes yield 10 times higher signal amplitudes than a total membrane extract from E.coli.
Author: Nanion Technologies, in cooperation with Dimitrios Fotiadis, University of Bern
Target (Synonyms): PR, pRhodopsin, Proteorhodopsine
Family / Type: Ion-translocating Microbial Rhodopsin Family (MRF, TCDB: 3.E.1)
Mode of transport: light-driven H+ pump
Sample: Purified membrane vesicles (total or inner plasma membranes via sucrose gradient)
Expression: recombinantly expressed in E.coli
Platform: SURFE2R N1
Background and Assay Description:
Before starting the measurement, the sensors have been exposed to light for 10 s to equilibrate the system and yield stable current signals for subsequent measurements. Then 50 ms light pulses have been repeated in 500 ms intervals using a green light LED (λmax = 530 ± 10 nm) with 20 mA intensity. When the light is turned on, Proteorhodpsin mediated proton efflux charges the sensor, which is measured as a negative transient current. When the light is turned off, the membrane potential relaxes to initial conditions. Protons leak along their electrochemical gradient, leading to a positive transient current. The same experiment has been performed using purified inner E.coli membranes and total E.coli membranes expressing PR. The recorded signal amplitude is 10 times increased within the purified sample. In addition, purified inner E.coli membranes without PR do not exhibit any signal upon exposure to light (black trace).