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Updated: Jul 11, 2026

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Published on: May 5, 2022
The structure of bacterial ParM filaments
Albina Orlova1, Ethan C Garner, Vitold E Galkin
1Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia 22908-0733, USA.
Abstract:
Bacterial ParM is a homolog of eukaryotic actin and is involved in moving plasmids so that they segregate properly during cell division. Using cryo-EM and three-dimensional reconstruction, we show that ParM filaments have a different structure from F-actin, with very different subunit-subunit interfaces. These interfaces result in the helical handedness of the ParM filament being opposite to that of F-actin. Like F-actin, ParM filaments have a variable twist, and we show that this involves domain-domain rotations within the ParM subunit. The present results yield new insights into polymorphisms within F-actin, as well as the evolution of polymer families.
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