ISSN:
0009-2851
Keywords:
Chemistry
;
Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
In active search for conditions for optimal phototrophic growth, halobacteria respond to light and to a variety of other environmental stimuli by taxis. Light reception is mediated by sensory rhodopsins, seven helix transmembrane retinal proteins that are stably complexed to specific MCP-related transducer proteins. Photoisomerization of the retinal chromophore generates a steric signal which activates the sensory rhodopsin-transducer-complex. Complex activation is relayed to a two component signaling system and transiently changes the cytoplasmic concentration of fumarate which, together with the small cytoplasmic protein CheY controls flagellar motor switching. Dual signaling by CheY and fumarate was also found in Escherichia coli where it mediates metabolic signaling and taxis in cells with disabled two-component system. Sensory integration of different environmental stimuli occurs at the level of the signaling domains of several stimulus-specific transducers constructed through combination of appropriate molecular modules. Irrespective of the complexity of the signaling network, the response to light is quantitatively predictable and stochastic. Its kinetic analysis suggests that time-dependent changes in the activity of signaling components can be resolved even in the context of a complex molecular network.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ciuz.19990330303
