• Illuminating a biological light switch

    From ScienceDaily@1:317/3 to All on Wed Jan 26 21:30:42 2022
    Illuminating a biological light switch

    Date:
    January 26, 2022
    Source:
    Weill Cornell Medicine
    Summary:
    Using an innovative new imaging technique, researchers have revealed
    the inner workings of a family of light-sensing molecules in
    unprecedented detail and speed. The work could inform new strategies
    in the burgeoning field of optogenetics, which uses light pulses
    to alter the activity of individual neurons and other cells.



    FULL STORY ========================================================================== Using an innovative new imaging technique, researchers at Weill Cornell Medicine have revealed the inner workings of a family of light-sensing molecules in unprecedented detail and speed. The work could inform new strategies in the burgeoning field of optogenetics, which uses light
    pulses to alter the activity of individual neurons and other cells.


    ========================================================================== Light-sensitive proteins drive many crucial processes in biology,
    ranging from photosynthesis to vision. Much of the science community's understanding of these proteins comes from studies on bacteriorhodopsin,
    a protein responsible for photosynthesis in certain single-celled
    organisms. Researchers have previously solved the three-dimensional
    structure of bacteriorhodopsin and studied its activity in detail,
    but the limitations of available techniques left puzzling gaps in the
    resulting models.

    The new study, published Dec. 10 in Nature Communications, describes a technique developed by the investigators, called line-scanning high-speed atomic force microscopy, that captures the motions of bacteriorhodopsin
    in response to light on a millisecond time scale.

    "The solution of protein structures has become quite straightforward,"
    said senior author Dr. Simon Scheuring, professor of physiology and
    biophysics in anesthesiology at Weill Cornell Medicine. "But a current challenge is to assess kinetics, which provide a dynamic understanding
    of the system." In particular, other methods that track the activity
    of individual molecules operate too slowly to reveal how the protein
    changes shape over short time periods, as bacteriorhodopsin appears to
    do in response to light. Dr. Scheuring compares these techniques to a
    movie camera with a slow shutter, which might capture a fast-moving bird
    at one side of the screen and then the other but be unable to track it
    in between those two points.

    Previously, researchers have tackled that problem by handicapping the
    bird: looking at variant forms of bacteriorhodopsin. "Up to now, to study
    the kinetics of bacteriorhodopsin, people were using mutants that were
    slower," said lead author Dr. Alma Perez Perrino, a postdoctoral fellow
    in Dr.

    Scheuring's laboratory. The slower variants don't represent the normal
    activity of the protein, though. To address that, Dr. Perez Perrino and
    her colleagues developed line-scanning high-speed atomic force microscopy, which sacrifices some image detail for a much faster frame rate, like
    taking blurrier images of the bird in order to follow it all the way
    across the screen.

    "We are tracking the protein every 1.6 milliseconds, so we could explore
    the speed of the wild-type bacteriorhodopsin," said Dr. Perez Perrino.

    In response to light, bacteriorhodopsin switches between open and closed states. Using their faster imaging technique, the researchers discovered
    that the transition to the open state and the duration of the open state
    always happen at the same speed, but the molecule remains in the closed
    state for longer periods as the intensity of the light decreases.

    Optogenetics researchers insert genes for light-sensing molecules in
    neurons or other cells, enabling them to change the cells' behavior with
    light pulses.

    That work has revolutionized neuroscience, and holds potential
    for treating neurological diseases as well. The more researchers
    know about light-sensing proteins, the further they'll be able
    to push optogenetics. "Ultimately, you want to switch on a
    process, then get the maximum out of it, and be able to switch
    it off again immediately," said Dr. Scheuring. "So, it is very
    important to know the kinetics of the molecules for that switching."
    special promotion Explore the latest scientific research on sleep and
    dreams in this free online course from New Scientist -- Sign_up_now_>>> ========================================================================== Story Source: Materials provided by Weill_Cornell_Medicine. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Alma P. Perrino, Atsushi Miyagi, Simon Scheuring. Single molecule
    kinetics of bacteriorhodopsin by HS-AFM. Nature Communications,
    2021; 12 (1) DOI: 10.1038/s41467-021-27580-2 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/01/220126122509.htm

    --- up 7 weeks, 4 days, 7 hours, 13 minutes
    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)