What does Halobacterium tell us about photoreception?

  title={What does Halobacterium tell us about photoreception?},
  author={Eilo Hildebrand},
  journal={Biophysics of structure and mechanism},
  • E. Hildebrand
  • Published 21 April 1977
  • Biology
  • Biophysics of structure and mechanism
A photosensory mechanism is proposed for Halobacterium halobium based on the observation of light-induced motor responses. Possible mechanisms of signal transduction in Halobacterium are discussed. Bacteriorhodopsin and the visual pigment rhodopsin are compared with respect to their structural and functional properties. The conclusion is drawn that Halobacterium may help to understand primary photochemical events of rhodopsin rather than the transduction mechanism of visual photoreceptors. 



Primary photophysical and photochemical processes in visual excitation

  • A. Lewis
  • Chemistry, Biology
    Biophysics of structure and mechanism
  • 2004
The color of visual pigments is experimentally shown to be controlled by excited state effects and the molecular changes observed are compared in bacterial and photoreceptor rhodopsins, yielding a unique explanation for the biological role of the cis-trans isomerization in visual transduction.

Flash photometric experiments on the photochemical cycle of bacteriorhodopsin

P pH-changes in the medium caused by the reaction cycle of bacteriorhodopsin were detected by use of the pH-indicator bromocresol green, and activation energy of the occurrence of these intermediates was calculated.

Functions of a new photoreceptor membrane.

Preliminary results indicate that the gradient in H. halobium plays the central role in energy coupling attributed to such electrochemical gradients by Mitchell's chemiosmotic theory.

Photoregeneration and Sensitivity Control of Photoreceptors of Invertebrates

In the octopus species Eledone moschata the wavelength maxima of the rhodopsin (R) and acid metarhodopsins (M) are separated by about 50 nm, so this R-M-system is well suited for photokinetic studies.

Photophosphorylation in Halobacterium halobium.

  • A. DanonW. Stoeckenius
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1974
Halobacterium halobium cells grown under semi-anaerobic conditions convert part of their cell membrane into "purple membrane" which contains a rhodopsin-like protein which uses the resulting chemiosmotic gradient for ATP synthesis.

Primary photochemical processes in bacteriorhodopsin.

Two photosystems controlling behavioural responses of Halobacterium halobium

Two photosystems are found which shows that bacteriorhodopsin is involved in the light-controlled motor response from H. halobium.

Rhodopsin-like protein from the purple membrane of Halobacterium halobium.

It is shown that the purple colour is due to retinal bound to an opsin-like protein, the only protein present in this membrane fragment, which has been isolated in relatively pure form from Halobacterium halobium.