Signaling and Adaptation Modulate the Dynamics of the Photosensoric Complex of Natronomonas pharaonis.
Motile bacteria and archaea respond to chemical and physical stimuli seeking optimal conditions for survival. To this end transmembrane chemo- and photoreceptors organized in large arrays initiate signaling cascades and ultimately regulate the rotation of flagellar motors. To unravel the molecular mechanism of signaling in an archaeal phototaxis complex we performed coarse-grained molecular dynamics simulations of a trimer of receptor/transducer dimers, namely NpSRII/NpHtrII from Natronomonas pharaonis. Signaling is regulated by a reversible methylation mechanism called adaptation, which also influences the level of basal receptor activation. Mimicking two extreme methylation states in our simulations we found conformational changes for the transmembrane region of NpSRII/NpHtrII which resemble experimentally observed light-induced changes. Further downstream in the cytoplasmic domain of the transducer the signal propagates via distinct changes in the dynamics of HAMP1, HAMP2, the adaptation domain and the binding region for the kinase CheA, where conformational rearrangements were found to be subtle. Overall these observations suggest a signaling mechanism based on dynamic allostery resembling models previously proposed for E. coli chemoreceptors, indicating similar properties of signal transduction for archaeal photoreceptors and bacterial chemoreceptors.
Department of Physics, University of Osnabrueck, Osnabrueck, Germany; Department of Biology, Lomonosov Moscow State University, Moscow, Russia.
Philipp S
PS
Orekhov
Department of Physics, University of Osnabrueck, Osnabrueck, Germany.
Daniel
D
Klose
Department of Physics, University of Osnabrueck, Osnabrueck, Germany; Department of Bioengineering and Bioinformatics and A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
Armen Y
AY
Mulkidjanian
Department of Biology, Lomonosov Moscow State University, Moscow, Russia.
Konstantin V
KV
Shaitan
Max-Planck-Institute for Molecular Physiology, Dortmund, Germany.
Martin
M
Engelhard
Department of Physics, University of Osnabrueck, Osnabrueck, Germany.
Johann P
JP
Klare
Department of Physics, University of Osnabrueck, Osnabrueck, Germany.
Heinz-Jürgen
HJ
Steinhoff
D000221:Adaptation, Ocular / Q000528:radiation effects; D019843:Archaeal Proteins / Q000737:chemistry / Q000528:radiation effects / Q000648:ultrastructure; D002338:Carotenoids / Q000737:chemistry / Q000528:radiation effects; D003198:Computer Simulation; D006216:Halobacteriaceae / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D010775:Photic Stimulation / Q000379:methods*; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure*; D011487:Protein Conformation / Q000528:radiation effects; D011829:Radiation Dosage
D019843:Archaeal Proteins; C434451:HtrII protein, Natronobacterium pharaonis; D020283:Photoreceptors, Microbial; C434450:phototaxis receptor sensory rhodopsin II, Natronobacterium pharaonis; D002338:Carotenoids