Helical Model of TubZ-Bt four-stranded filament

Experimental Data Snapshot

  • Resolution: 6.80 Å
  • Aggregation State: FILAMENT 
  • Reconstruction Method: HELICAL 

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This is version 1.3 of the entry. See complete history


Bacterial tubulin TubZ-Bt transitions between a two-stranded intermediate and a four-stranded filament upon GTP hydrolysis.

Montabana, E.A.Agard, D.A.

(2014) Proc Natl Acad Sci U S A 111: 3407-3412

  • DOI: https://doi.org/10.1073/pnas.1318339111
  • Primary Citation of Related Structures:  
    3J4S, 3J4T

  • 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.

  • Organizational Affiliation

    Department of Biochemistry and Biophysics, and Howard Hughes Medical Institute, University of California, San Francisco, CA 94158.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
FtsZ/tubulin-related protein484Bacillus thuringiensis serovar israelensisMutation(s): 0 
Gene Names: pBt156
Find proteins for Q8KNP3 (Bacillus thuringiensis subsp. israelensis)
Explore Q8KNP3 
Go to UniProtKB:  Q8KNP3
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8KNP3
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on GDP

Download Ideal Coordinates CCD File 
C10 H15 N5 O11 P2
Experimental Data & Validation

Experimental Data

  • Resolution: 6.80 Å
  • Aggregation State: FILAMENT 
  • Reconstruction Method: HELICAL 
EM Software:
TaskSoftware PackageVersion

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-02-19
    Type: Initial release
  • Version 1.1: 2014-03-05
    Changes: Database references
  • Version 1.2: 2014-03-19
    Changes: Database references
  • Version 1.3: 2018-07-18
    Changes: Author supporting evidence, Data collection