Single-Molecule Force Spectroscopy Measures Structural Changes Induced by Light Activation and Transducer Binding in Sensory Rhodopsin II |
| |
Authors: | Leoni Oberbarnscheidt Swetlana Martell Filipp Oesterhelt |
| |
Institution: | 1 Institut für molekulare physikalische Chemie, Universitätsstr. 1, 40225 Düsseldorf, Germany 2 Max-Planck-Institut für molekulare Physiologie, Otto-Hahn-Str. 11, 44227 Dortmund, Germany |
| |
Abstract: | Microbial rhodopsins are a family of seven-helical transmembrane proteins containing retinal as chromophore. Sensory rhodopsin II (SRII) triggers two very different responses upon light excitation, depending on the presence or the absence of its cognate transducer HtrII: Whereas light activation of the NpSRII/NpHtrII complex activates a signalling cascade that initiates the photophobic response, NpSRII alone acts as a proton pump.Using single-molecule force spectroscopy, we analysed the stability of NpSRII and its complex with the transducer in the dark and under illumination. By improving force spectroscopic data analysis, we were able to reveal the localisation of occurring forces within the protein chain with a resolution of about six amino acids. Distinct regions in helices G and F were affected differently, depending on the experimental conditions. The results are generally in line with previous data on the molecular stability of NpSRII. Interestingly, new interaction sites were identified upon light activation, whose functional importance is discussed in detail. |
| |
Keywords: | SRII sensory rhodopsin II SMFS single-molecule force spectroscopy AFM atomic force microscopy WLC worm-like chain EPR electron paramagnetic resonance FRET fluorescence resonance energy transfer |
本文献已被 ScienceDirect 等数据库收录! |
|