Bacillus licheniformis Anti-TRAP can assemble into two types of dodecameric particles with the same symmetry but inverted orientation of trimers.
Anti-TRAP (AT) protein regulates expression of tryptophan biosynthetic genes by binding to the trp RNA-binding attenuation protein (TRAP) and preventing its interaction with RNA. Bacillus subtilis AT forms trimers that can either interact with TRAP or can further assemble into dodecameric particles. To determine which oligomeric forms are preserved in AT proteins of other Bacilli we studied Bacillus licheniformis AT which shares 66% sequence identity with the B. subtilis protein. We show that in solution B. licheniformis AT forms stable trimers. In crystals, depending on pH, such trimers assemble into two different types of dodecameric particles, both having 23 point group symmetry. The dodecamer formed at pH 6.0 has the same conformation as previously observed for B. subtilis AT. This dodecamer contains a large internal chamber with the volume of approximately 700 A(3), which is lined by the side chains of twelve valine residues. The presence of the hydrophobic chamber hints at the possibility that the dodecamer formation could be induced by binding of a ligand. Interestingly, in the dodecamer formed at pH 8.0 all trimers are turned inside out relatively to the form observed at pH 6.0.
York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO1 5YW, UK.
Mikhail B
MB
Shevtsov
Yanling
Y
Chen
Michail N
MN
Isupov
Andrew
A
Leech
Paul
P
Gollnick
Alfred A
AA
Antson
D000595:Amino Acid Sequence; D001407:Bacillus / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D001483:Base Sequence; D018360:Crystallography, X-Ray; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D008969:Molecular Sequence Data; D055503:Protein Multimerization; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D017385:Sequence Homology; D013045:Species Specificity; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D014364:Tryptophan / Q000096:biosynthesis*; D014461:Ultracentrifugation
D001426:Bacterial Proteins; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C435924:yczA protein, Bacillus subtilis; D014364:Tryptophan