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Per-ARNT-Sim (PAS) domains serve as versatile sensor and interaction modules in signal transduction proteins. PAS sensors detect chemical and physical stimuli and regulate the activity of functionally diverse effector domains. In contrast to this chemical, physical, and functional diversity, the structure of the core of PAS domains is broadly conserved and(More)
Signal transduction proteins are organized into sensor (input) domains that perceive a signal and, in response, regulate the biological activity of effector (output) domains. We reprogrammed the input signal specificity of a normally oxygen-sensitive, light-inert histidine kinase by replacing its chemosensor domain by a light-oxygen-voltage photosensor(More)
Cellular processes and indeed the survival of entire organisms crucially depend on precise spatiotemporal coordination of a multitude of molecular events. A new tool in cell biology is denoted "optogenetics" which describes the use of genetically encoded, light-gated proteins, i.e. photoreceptors, which perturb and control cellular and organismal behavior(More)
Signaling photoreceptors use the information contained in the absorption of a photon to modulate biological activity in plants and a wide range of organisms. The fundamental-and as yet imperfectly answered-question is, how is this achieved at the molecular level? We adopt the perspective of biophysicists interested in light-dependent signal transduction in(More)
Two-component systems (TCSs), which comprise sensor histidine kinases (SHK) and response-regulator proteins, represent the predominant strategy by which prokaryotes sense and respond to a changing environment. Despite paramount biological importance, a dearth exists of intact SHK structures containing both sensor and effector modules. Here, we report the(More)
Glycine and proline residues are frequently found in turn and loop structures of proteins and are believed to play an important role during chain compaction early in folding. We investigated their effect on the dynamics of intrachain loop formation in various unstructured polypeptide chains. Loop formation is significantly slower around trans prolyl peptide(More)
The foldon domain constitutes the C-terminal 30 amino acid residues of the trimeric protein fibritin from bacteriophage T4. Its function is to promote folding and trimerization of fibritin. We investigated structure, stability and folding mechanism of the isolated foldon domain. The domain folds into the same trimeric beta-propeller structure as in fibritin(More)
Characterization of the unfolded state is essential for the understanding of the protein folding reaction. We performed time-resolved FRET measurements to gain information on the dimensions and the internal dynamics of unfolded polypeptide chains. Using an approach based on global analysis of data obtained from two different donor-acceptor pairs allowed for(More)
the transition between these states (Fig. 1). When photons activate channelrhodopsin in its DA state, the channel reaches the O1 state. In conditions of continuous light, channel-rhodopsin reaches an equilibrium consisting of O1 and O2 states. As the O2 state is less permeant for Na + than the O1 state is, the transition from the O1 state to the O2 state(More)
Signaling photoreceptors mediate diverse organismal adaptations in response to light. As light-gated protein switches, signaling photoreceptors provide the basis for optogenetics, a term that refers to the control of organismal physiology and behavior by light. We establish as novel optogenetic tools the plasmids pDusk and pDawn, which employ blue-light(More)