Improved resolution crystal structure of Acanthamoeba actophorin reveals structural plasticity not induced by microgravity. Issue 12 (11th November 2021)

• Record Type: Journal Article
• Authors: Quirk, Stephen; Lieberman, Raquel L.
• Is Part Of: Acta crystallographica. Volume 77:Issue 12(2021)
• Page Start: 452
• Page End: 458
• Publication Date: 2021-11-11
• Subjects: microgravity -- actophorin -- actin -- Acanthamoeba castellanii -- cofilin -- conformational change; Crystallography -- Periodicals; Crystals -- Periodicals; 548
• DOI: 10.1107/S2053230X21011419
• Languages: English
• ISSNs: 2053-230X

Abstract

Abstract : Crystals of actophorin were grown in microgravity in an interactive process with astronauts on the International Space Station. Although the diffraction was not improved compared with crystals grown on Earth, a conformational change suggestive of motions intrinsic to actophorin function was observed. Abstract : Actophorin, a protein that severs actin filaments isolated from the amoeba Acanthamoeba castellanii, was employed as a test case for crystallization under microgravity. Crystals of purified actophorin were grown under microgravity conditions aboard the International Space Station (ISS) utilizing an interactive crystallization setup between the ISS crew and ground‐based experimenters. Crystals grew in conditions similar to those grown on earth. The structure was solved by molecular replacement at a resolution of 1.65 Å. Surprisingly, the structure reveals conformational changes in a remote β‐turn region that were previously associated with actophorin phosphorylated at the terminal residue Ser1. Although crystallization under microgravity did not yield a higher resolution than crystals grown under typical laboratory conditions, the conformation of actophorin obtained from solving the structure suggests greater flexibility in the actophorin β‐turn than previously appreciated and may be beneficial for the binding of actophorin to actin filaments.