3J4T

Helical model of TubZ-Bt two-stranded filament

Summary for 3J4T

• Entry DOI: 10.2210/pdb3j4t/pdb
• Related: 2XKA 3J4T
• EMDB information: 5762 5763
• Descriptor: FtsZ/tubulin-related protein (1 entity in total)
• Functional Keywords: tubz, ftsz-like, tubulin-like, plasmid segregation, structural protein
• Biological source: Bacillus thuringiensis
• Total number of polymer chains: 1
• Total formula weight: 55052.44

Authors

Agard, D.A.,Montabana, E.A. (deposition date: 2013-10-04, release date: 2014-02-19, Last modification date: 2024-02-21)

Primary citation

Montabana, E.A.,Agard, D.A.
Bacterial tubulin TubZ-Bt transitions between a two-stranded intermediate and a four-stranded filament upon GTP hydrolysis.
Proc.Natl.Acad.Sci.USA, 111:3407-3412, 2014

PubMed Abstract: Cytoskeletal filaments form diverse superstructures that are highly adapted for specific functions. The recently discovered TubZ subfamily of tubulins is involved in type III plasmid partitioning systems, facilitating faithful segregation of low copy-number plasmids during bacterial cell division. One such protein, TubZ-Bt, is found on the large pBtoxis plasmid in Bacillus thuringiensis, and interacts via its extended C terminus with a DNA adaptor protein TubR. Here, we use cryo-electron microscopy to determine the structure of TubZ-Bt filaments and light scattering to explore their mechanism of polymerization. Surprisingly, we find that the helical filament architecture is remarkably sensitive to nucleotide state, changing from two-stranded to four-stranded depending on the ability of TubZ-Bt to hydrolyze GTP. We present pseudoatomic models of both the two- and four-protofilament forms based on cryo-electron microscopy reconstructions (10.8 Å and 6.9 Å, respectively) of filaments formed under different nucleotide states. These data lead to a model in which the two-stranded filament is a necessary intermediate along the pathway to formation of the four-stranded filament. Such nucleotide-directed structural polymorphism is to our knowledge an unprecedented mechanism for the formation of polar filaments.

PubMed: 24550513
DOI: 10.1073/pnas.1318339111

Experimental method

ELECTRON MICROSCOPY (10.8 Å)