Humboldt-Universität zu Berlin - Experimentelle Biophysik

Dr. Meike Luck  



Room:    401


Tel:       (030) 2093 98462


Project: Histidine Kinase Rhodopsins

The alga Chlamydomonas reinhardtii contains, besides the flavin-based photoreceptors(phototropin, cryptochrome), eight rhodopsin-related proteins of very unusual structure and function. Well understood are only the two channelrhodopsins ChR1 and ChR2, whereas the 4 histidine-kinase Rhodopsins (HKRs) are neither studied with respect to biophysical properties nor to their cellular function. HKRs in C. reinhardtii are representatives of Two Component Signaling systems (TCS) unified in a single protein unity. As concluded from the sequences each rhodopsinis linked to a His-Kinase (HK), a response regulator (RR) and in some cases to an effector domain that might be an adenylyl cyclase or guanylyl cyclase (cyc). Very recently, sequences encoding HKRs were also found in other unicellular algae, for example in the marine microalgae Ostreococcustauri and Micromonaspusilla, indicating the physiological and evolutionary relevance of this photoreceptor family.

In this project the light absorbing properties of the isolated rhodopsin domains are investigated by UV/Vis- and vibrational spectroscopic methods. These measurements revealed an unusual behavior with respect to their photocyclesin comparison to other microbial rhodopsins. Additionally, functional studies regarding the signal transduction cascade and the enzymatic activity are one of the main objects.




Bruun S, Stoeppler D, Keidel A, Kuhlmann U, Luck M, Diehl A, Geiger MA, Woodmansee D, Trauner D, Hegemann P, Oschkinat H, Hildebrandt P, Stehfest K.(2015) Light-Dark Adaptation of Channelrhodopsin Involves Photoconversion between the all-trans and 13-cis Retinal Isomers. Biochemistry. Sep 8;54(35):5389-400. doi: 10.1021/acs.biochem.5b00597. Epub 2015 Aug 20.


Luck M, Bruun S, Keidel A, Hegemann P, Hildebrandt P. 2015 Photochemical chromophore isomerization in histidine kinase rhodopsin HKR1. FEBS Lett. 589:1067-71.


Penzkofer, A., Luck, M., Mathes, T., Hegemann, P. (2014) Bistable retinal Schiff base photo-dynamics of histidine kinase rhodopsin HKR1 from Chlamy¬domonas reinhardtii. Photochem.Photobiol. 90(4), 773-85.


Penzkofer, A., Luck, M., Mathes, T., Hegemann, P. (2014). Ultrafast laser energy density and retinal absorption cross-section determination by saturable absorption measurements. Journal of Analytical Sciences, Methods and Instrumentation (JASMI) 4, 19-26.;


Luck M, Mathes T, Bruun S, Fudim R, Hagedorn R, Nguyen TM, Kateriya S, Kennis JT, Hildebrandt P, Hegemann P (2012). A photochromic histidine kinase rhodopsin (HKR1) that is bimodally switched by UV and blue light. J BiolChem 287:40083–40090