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The Crystal Structure of the Ca2+-ATPase 1 from Listeria monocytogenes reveals a Pump Primed for Dephosphorylation

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Many bacteria export intracellular calcium using active transporters homologous to the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA). Here we present three crystal structures of Ca2+-ATPase 1 from Listeria monocytogenes (LMCA1). Structures with BeF3- mimicking a phosphoenzyme state reveal a closed state, which is intermediate between the outward-open E2P and the proton-occluded E2-P* conformations known for SERCA. It suggests that LMCA1 in the E2P state is pre-organized for dephosphorylation upon Ca2+ release, consistent with the rapid dephosphorylation observed in single-molecule studies. An arginine side-chain occupies the position equivalent to calcium binding site I in SERCA, leaving a single Ca2+ binding site in LMCA1, corresponding to SERCA site II. Observing no putative transport pathways dedicated to protons, we infer a direct proton counter transport through the Ca2+ exchange pathways. The LMCA1 structures provide insight into the evolutionary divergence and conserved features of this important class of ion transporters.

TidsskriftJournal of Molecular Biology
StatusUdgivet - aug. 2021

Bibliografisk note

Funding Information:
This work has been supported by grants to P.N. from the Lundbeck Foundation (DANDRITE-R248-2016-2518) and the Independent Research Fund Denmark (FNU) (7014-00328B). S.B.H. was supported by a Ph.D. fellowship from the Boehringer Ingelheims Fond. The authors are grateful for early target identification by J. Preben Morth and the technical assistance of Anna Marie Nielsen and Tanja Klymchuk. We further thank the staff at the EMBL beamline P13 at the PETRA3 synchrotron in Hamburg for access and technical support.

Publisher Copyright:
© 2021 The Authors

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