The Signal Transfer from the Receptor NpSRII to the Transducer NpHtrIl Is Not Hampered by the D75N Mutation
Autor(en): | Holterhues, Julia Bordignon, Enrica Klose, Daniel Rickert, Christian Klare, Johann P. Martell, Swetlana Li, Lin Engelhard, Martin Steinhofft, Heinz-Juergen |
Stichwörter: | Biophysics; COLOR DISCRIMINATION; DOMAIN; HELIX-F; MICROBIAL RHODOPSINS; NATRONOBACTERIUM-PHARAONIS; NATRONOMONAS-PHARAONIS; PHOTOCYCLE; SENSORY-RHODOPSIN-II; TIME-RESOLVED DETECTION; TRANSIENT MOVEMENT | Erscheinungsdatum: | 2011 | Herausgeber: | CELL PRESS | Journal: | BIOPHYSICAL JOURNAL | Volumen: | 100 | Ausgabe: | 9 | Startseite: | 2275 | Seitenende: | 2282 | Zusammenfassung: | Sensory rhodopsin II (NpSRII) is a phototaxis receptor of Natronomonas pharaonis that performs its function in complex with its cognate transducer (NpHtrII). Upon light activation NpSRII triggers by means of NpHtrII a signal transduction chain homologous to the two component system in eubacterial chemotaxis. The D75N mutant of NpSRII, which lacks the blue-shifted M intermediate and therefore exhibits a significantly faster photocycle compared to the wild-type, mediates normal phototaxis responses demonstrating that deprotonation of the Schiff base is not a prerequisite for transducer activation. Using site-directed spin labeling and time resolved electron paramagnetic-resonance spectroscopy, we show that the mechanism revealed for activation of the wild-type complex, namely an outward tilt motion of the cytoplasmic part of the receptor helix F and a concomitant rotation of the transmembrane transducer helix TM2, is also valid for the D75N variant. Apparently, the D75N mutation shifts the ground state conformation of NpSRII-D75N and its cognate transducer into the direction of the signaling state. |
ISSN: | 00063495 | DOI: | 10.1016/j.bpj.2011.03.017 |
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geprüft am 15.05.2024