Architecture and Assembly of a Divergent Member of the ParM Family of Bacterial Actin-like Proteins

Eubacteria and archaea contain a variety of actin-like proteins (ALPs) that form filaments with surprisingly diverse architectures, assembly dynamics, and cellular functions. Although there is much data supporting differences between ALP families, there is little data regarding conservation of struc...

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Bibliographic Details
Published in:The Journal of biological chemistry 2011-04, Vol.286 (16), p.14282-14290
Main Authors: Rivera, Christopher R., Kollman, Justin M., Polka, Jessica K., Agard, David A., Mullins, R. Dyche
Format: Article
Language:English
Subjects:
Actin
Actin Cytoskeleton - chemistry
Actins - chemistry
Actins - metabolism
Adenosine Triphosphate - chemistry
Bacteria
Bacterial Actin-like Filaments
Cell Biology
Cloning, Molecular
DNA - chemistry
Electron Microscopy (EM)
Escherichia coli Proteins - metabolism
Image Processing, Computer-Assisted
Kinetics
Microfilaments
Models, Biological
Phosphates - chemistry
Plasmid Segregation Proteins
Plasmids - metabolism
Polymers - chemistry
Presteady-state Kinetics
Protein Assembly
Protein Conformation
Proteins - chemistry
Scattering, Radiation
TIRF Microscopy
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Summary:Eubacteria and archaea contain a variety of actin-like proteins (ALPs) that form filaments with surprisingly diverse architectures, assembly dynamics, and cellular functions. Although there is much data supporting differences between ALP families, there is little data regarding conservation of structure and function within these families. We asked whether the filament architecture and biochemical properties of the best-understood prokaryotic actin, ParM from plasmid R1, are conserved in a divergent member of the ParM family from plasmid pB171. Previous work demonstrated that R1 ParM assembles into filaments that are structurally distinct from actin and the other characterized ALPs. They also display three biophysical properties thought to be essential for DNA segregation: 1) rapid spontaneous nucleation, 2) symmetrical elongation, and 3) dynamic instability. We used microscopic and biophysical techniques to compare and contrast the architecture and assembly of these related proteins. Despite being only 41% identical, R1 and pB171 ParMs polymerize into nearly identical filaments with similar assembly dynamics. Conservation of the core assembly properties argues for their importance in ParM-mediated DNA segregation and suggests that divergent DNA-segregating ALPs with different assembly properties operate via different mechanisms.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M110.203828