Interaction of the trp RNA-binding attenuation protein (TRAP) with anti-TRAP.
The trp RNA-binding attenuation protein (TRAP) negatively regulates expression of the tryptophan biosynthesis genes of Bacillus subtilis. In the presence of tryptophan, TRAP is activated to bind to the 5'-leader region of the trp mRNA resulting in termination prior to the structural genes. In addition, accumulation of uncharged tRNA(Trp) induces synthesis of anti-TRAP (AT), which binds to TRAP and inhibits its function. Both of these proteins consist of oligomers of identical subunits. Here, we characterize the self-association of each of these proteins and the TRAP-AT interaction in free solution using equilibrium and velocity analytical ultracentrifugation. TRAP exists as a stable 11-mer in the absence and in the presence of tryptophan. Tryptophan binding induces a conformational change in TRAP. AT exists in a reversible equilibrium between trimer and dodecamer with an equilibrium constant of approximately 3 x 10(14)M(-3). About 20% of the trimer is incompetent to form dodecamer. The AT equilibrium is slow on the time-scale of the velocity experiment. Formation of TRAP-AT complexes occurs only in the presence of tryptophan. A complex containing one TRAP 11-mer and one AT 12-mer forms with high affinity. At higher ratios of TRAP:AT complexes containing two TRAP 11-mers and one AT 12-mer are detected. A model for the structure of the complex is proposed.
Snyder
Doug
D
Department of Molecular and Cell Biology, University of Connecticut, 91 N. Eagleville Road, U-3125, Storrs, CT 06269, USA.
Lary
Jeffrey
J
Chen
Yanling
Y
Gollnick
Paul
P
Cole
James L
JL
D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D046911:Macromolecular Substances; D008958:Models, Molecular; D011485:Protein Binding; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism; D014461:Ultracentrifugation
D001426:Bacterial Proteins; D046911:Macromolecular Substances; C079092:MtrB protein, Bacteria; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C435924:yczA protein, Bacillus subtilis; D014364:Tryptophan