4 research outputs found
Strukturelle und funktionelle Untersuchungen des Transducers HtrII aus Natronomonas pharaonis und von HtrII/Tar-Chimären
Salt-driven Equilibrium between Two Conformations in the HAMP Domain from Natronomonas pharaonis: THE LANGUAGE OF SIGNAL TRANSFER?*
HAMP domains (conserved in histidine kinases, adenylyl cyclases,
methyl-accepting chemotaxis proteins, and phosphatases) perform their putative
function as signal transducing units in diversified environments in a variety
of protein families. Here the conformational changes induced by environmental
agents, namely salt and temperature, on the structure and function of a HAMP
domain of the phototransducer from Natronomonas pharaonis (NpHtrII)
in complex with sensory rhodopsin II (NpSRII) were investigated by
site-directed spin labeling electron paramagnetic resonance. A series of spin
labeled mutants were engineered in NpHtrII157, a truncated analog
containing only the first HAMP domain following the transmembrane helix 2.
This truncated transducer is shown to be a valid model system for a signal
transduction domain anchored to the transmembrane light sensor NpSRII. The
HAMP domain is found to be engaged in a “two-state” equilibrium
between a highly dynamic (dHAMP) and a more compact (cHAMP)
conformation. The structural properties of the cHAMP as proven by
mobility, accessibility, and intra-transducer-dimer distance data are in
agreement with the four helical bundle NMR model of the HAMP domain from
Archaeoglobus fulgidus