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RESEARCH PRODUCT
Tracking Ca2+ ATPase intermediates in real time by x-ray solution scattering
Matteo LevantinoMatteo LevantinoMartin Nors PedersenChenge LiMagnus AnderssonMattias EklundMichael WulffAndreas BarthAljona SitselAnnette DuelliPoul NissenClaus OlesenHarsha Ravishankarsubject
CONFORMATIONAL-CHANGESSERCAATPaseAtom and Molecular Physics and OpticsPUMPSTRUCTURAL DYNAMICSchemistry.chemical_elementCalciumCA2+-ATPASE03 medical and health sciencesPHOSPHOENZYME030304 developmental biologyCalcium signaling0303 health sciencesMultidisciplinarybiologyEndoplasmic reticulum030302 biochemistry & molecular biologySARCOPLASMIC-RETICULUMSettore FIS/07 - Fisica Applicata(Beni Culturali Ambientali Biol.e Medicin)MembranechemistryATPase time-resolved X-ray solution scatteringCytoplasmMOLECULAR-DYNAMICSbiology.proteinBiophysicsPhosphorylationSKELETAL-MUSCLEAtom- och molekylfysik och optikMEMBRANECALCIUM-TRANSPORTdescription
Sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) transporters regulate calcium signaling by active calcium ion reuptake to internal stores. Structural transitions associated with transport have been characterized by x-ray crystallography, but critical intermediates involved in the accessibility switch across the membrane are missing. We combined time-resolved x-ray solution scattering (TR-XSS) experiments and molecular dynamics (MD) simulations for real-time tracking of concerted SERCA reaction cycle dynamics in the native membrane. The equilibrium [Ca2] E1 state before laser activation differed in the domain arrangement compared with crystal structures, and following laser-induced release of caged ATP, a 1.5-ms intermediate was formed that showed closure of the cytoplasmic domains typical of E1 states with bound Ca2+ and ATP. A subsequent 13-ms transient state showed a previously unresolved actuator (A) domain arrangement that exposed the ADP-binding site after phosphorylation. Hence, the obtained TR-XSS models determine the relative timing of so-far elusive domain rearrangements in a native environment.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2020-01-01 |