Received: 14 June 2021
Accepted: 15 July 2021
First Online: 16 August 2021
Compliance with Ethical Standards
: The authors declare that they have no conflict of interest.
: This article does not contain any studies with human or animal subjects performed by any of the authors.
: Final refined coordinates and structure factors have been deposited in the Protein Data Bank (PDB) under accession code 7EXM.
Free to read: This content has been made available to all.