These two authors contributed equally to this work.
Interaction of the Halobacterial Transducer to a Halorhodopsin Mutant Engineered so as to Bind the Transducer: Cl− Circulation Within the Extracellular Channel†
Article first published online: 27 FEB 2007
Photochemistry and Photobiology
Volume 83, Issue 2, pages 293–302, March/April 2007
How to Cite
Hasegawa, C., Kikukawa, T., Miyauchi, S., Seki, A., Sudo, Y., Kubo, M., Demura, M. and Kamo, N. (2007), Interaction of the Halobacterial Transducer to a Halorhodopsin Mutant Engineered so as to Bind the Transducer: Cl− Circulation Within the Extracellular Channel. Photochemistry and Photobiology, 83: 293–302. doi: 10.1562/2006-06-09-RA-916
This paper is part of the Proceedings of the 12th International Conference on Retinal Proteins held at Awaji Island, Hyogo, Japan on 4–8 June 2006.
- Issue published online: 27 FEB 2007
- Article first published online: 27 FEB 2007
- Received 9 June 2006; accepted 11 September 2006; published online 14 September 2006
An alkali-halophilic archaeum, Natronomonas pharaonis, contains two rhodopsins that are halorhodopsin (phR), a light-driven inward Cl− pump and phoborhodopsin (ppR), the receptor of negative phototaxis functioning by forming a signaling complex with a transducer, pHtrII (Sudo Y. et al., J. Mol. Biol. 357  1274). Previously, we reported that the phR double mutant, P240T/F250YphR, can bind with pHtrII. This mutant itself can transport Cl−, while the net transport was stopped upon formation of the complex. The flash-photolysis data were analyzed by a scheme in which phR→P1→P2→P3→P4→phR. The P3 of the wild-type and the double mutant contained two components, X- and O-intermediates. After the complex formation, however, the P3 of the double mutant lacked the X-intermediate. These observations imply that the X-intermediate (probably the N-intermediate) is the state having Cl− in the cytoplasmic binding site and that the complex undergoes an extracellular Cl− circulation because of the inhibition of formation of the X-intermediate.