Salt-driven equilibrium between two conformations in the HAMP domain from Natronomonas pharaonis - The language of signal transfer?
Autor(en): | Doebber, Meike Bordignon, Enrica Klare, Johann P. Holterhues, Julia Martell, Swetlana Mennes, Nadine Li, Lin Engelhard, Martin Steinhoff, Heinz-Juergen |
Stichwörter: | BACTERIORHODOPSIN; Biochemistry & Molecular Biology; COMPLEX; HISTIDINE KINASE; NITROXIDE MOTION; PHOBORHODOPSIN; PHOTOTRANSDUCER; SENSORY RHODOPSIN II; SIDE-CHAINS; SPIN-LABELED PROTEINS; STRUCTURAL DETERMINANTS | Erscheinungsdatum: | 2008 | Herausgeber: | ELSEVIER | Journal: | JOURNAL OF BIOLOGICAL CHEMISTRY | Volumen: | 283 | Ausgabe: | 42 | Startseite: | 28691 | Seitenende: | 28701 | Zusammenfassung: | 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 NpHtrII(157), 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. |
DOI: | 10.1074/jbc.M801931200 |
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