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SUMMARY:The importance of water in biology - an example of receptor functi
 on and implications for optogenetics
DTSTART;VALUE=DATE-TIME:20260326T120000Z
DTEND;VALUE=DATE-TIME:20260326T124000Z
DTSTAMP;VALUE=DATE-TIME:20260426T115551Z
UID:indico-contribution-10331@events.saip.org.za
DESCRIPTION:Speakers: Anthony Watts (University of Oxford)\nWater\, in its
  many states\, has a pivotal role in biology. But resolving it at the mole
 cular level has been a challenge. Here\, we resolve and describe how water
  determines the way in which an external stimulus\, light in this example\
 , intimately controls how the stimulus is conformational changes in membra
 ne receptors in response to a stimulus\, and capturing their functionally 
 relevant dynamics\, is very challenging. Over the years we have addressed 
 this challenge using a range of spectroscopic approaches [1\,2\,3] on func
 tionally competent photoreceptors\, often in their natural membranes [4] o
 r Lipodisqs™ [5\,6]. More recently\, we have complemented this work with
  functional studies\, mass spec characterization [7] and very high resolut
 ion (1.07 Å) crystallography [8\,9\,10]\, as well as photo-induced x-ray\
 , free electron laser studies (XFELS)\, without the use of detergents and 
 including natural lipids. This high-resolution information reveals waters 
 and their importance in both receptor activation-desensitization and QM(SC
 C-DFTB)/MM MD trajectories give information about the activation process. 
 The system studied is achearhodopsin-3 (AR3)\, a photoreceptor utilized wi
 dely in optogenetics despite the lack of structures until now. We suggest 
 that the different arrangement of internal water networks in AR3 is respon
 sible for the faster photocycle kinetics compared to homologs – AR3 is ~
 10x more efficient than bacteriorhodopsin at current generation. These ins
 ights may well have generic implications for other receptors.\n\n(1). Higm
 an et al.\, (2011) Angew. Chemie 50(36):8432\n(2). Dijkman et al.\, (2018)
  Nature Comms. 9:1710\n(3). Dijkman et al.\, (2020) Science Advances\, 6:3
 3\n(4). Lavington & Watts (2020) Biophys. Rev. 12:1287\n(5). Juarez et al.
 \, (2019) Chem. Phys. Lipids 221:167\n(6). Sawczyc et al (2023) Eur. Bioph
 ys J. 52:39\n(7). Hoi et al.\, (2021) Nano Letters\, 21(7):2824\n(8). Axfo
 rd et al.\, (2022) Acta Cryst D78:52\n(9). Juarez et al (2021) Nature Comm
 s. 12:629\n(10). Birsh et al.\, (2023) J. Appl. Cryst. 56:1361\n\nhttps://
 events.saip.org.za/event/272/contributions/10331/
LOCATION:
URL:https://events.saip.org.za/event/272/contributions/10331/
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