| Chlamyrhodopsin 5 and 6 - enzymatically active rhodopsins |
| Meike Luckand Peter Hegemann |
| Experimental Biophysics, Humboldt University of Berlin, 10115 Berlin, Germany |
| In the green alga Chlamydomonas reinhardtii exist at least 7 Rhodopsin related proteins (Chlamyopsins, Cop) with different functions. Cop5 and Cop6 belong to a group of hypothetical "enzyme-rhodopsins". The two proteins consist of 4 putative protein domains: the N-terminal rhodopsin is followed by a His-Kinase, a Response regulator and a C-terminal guanylate-cyclase as effector domain [1]. A big part of Cop6 and parts of Cop5 are already verified by RT-PCR. Three constructs, namely Cop5, a hybrid of Cop5 with the Cop6 cyclase-domain, and Cop6 are expressed in Xenopus Oocytes. The expression is detected via western-blotting. By mutation of two aminoacids we intend to change the specifity of the Cop6-cyclase into an adenylate-cyclase-activity. By coexpression of a cyclic nucleotide-gated channel we hope that we are able to demonstrate the light-induced production of cGMP and cAMP [2]. Furthermore we will express the Cop6-cyclase seperately in Xenopus Oocytes and monitor the constitutive activity independent of the rhodopsin and signalling partners, His-kinase and RR. The rhodopsin-domains of Cop5 and Cop6 are expressed in Cos-cells. The protein is purified for spectroscopical investigations. The goal of the project is a concise characterization of the first members of the enzyme-rhodopsin family.
[1] S. Kateriya, G. Nagel, E. Bamberg, P. Hegemann, News Physiol Sci 19 (2004) 133-137 |
| e-mail address of presenting author: meikeluck@freenet.de |