Uncovering the early stages of domain melting in calmodulin with ultrafast temperature-jump infrared spectroscopy

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Minnes, Lucy and Greetham, Gregory M. and Shaw, Daniel J. and Clark, Ian P. and Fritzsch, Robby and Towrie, Michael and Parker, Anthony W. and Henry, Alistair J. and Taylor, Richard J. and Hunt, Neil T. (2019) Uncovering the early stages of domain melting in calmodulin with ultrafast temperature-jump infrared spectroscopy. Journal of Physical Chemistry B, 123 (41). pp. 8733-8739. ISSN 1520-6106 (https://doi.org/10.1021/acs.jpcb.9b08870)

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Abstract

The signaling protein calmodulin (CaM) undergoes a well-known change in secondary structure upon binding Ca2+, but the structural plasticity of the Ca2+-free apo state is linked to CaM functionality. Variable temperature studies of apo-CaM indicate two structural transitions at 46 and 58 °C that are assigned to melting of the C- and N-terminal domains, respectively, but the molecular mechanism of domain unfolding is unknown. We report temperature-jump time-resolved infrared (IR) spectroscopy experiments designed to target the first steps in the C-terminal domain melting transition of human apo-CaM. A comparison of the nonequilibrium relaxation of apo-CaM with the more thermodynamically stable holo-CaM, with 4 equiv of Ca2+ bound, shows that domain melting of apo-CaM begins on microsecond time scales with α-helix destabilization. These observations enable the assignment of previously reported dynamics of CaM on hundreds of microsecond time scales to thermally activated melting, producing a complete mechanism for thermal unfolding of CaM.

ORCID iDs

Minnes, Lucy ORCID logoORCID: https://orcid.org/0000-0001-7476-6023, Greetham, Gregory M., Shaw, Daniel J., Clark, Ian P., Fritzsch, Robby ORCID logoORCID: https://orcid.org/0000-0003-0198-1691, Towrie, Michael, Parker, Anthony W., Henry, Alistair J., Taylor, Richard J. and Hunt, Neil T.;
  • Item type:Article
    ID code:70362
    Dates:
    Date
    Event
    17 October 2019
    Published
    26 September 2019
    Published Online
    26 September 2019
    Accepted
    Subjects:Science > Chemistry
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:31 Oct 2019 09:52
    Last modified:18 Dec 2024 05:58
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/70362
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