Dynamic allostery in the ring protein TRAP.
We have discovered distinct, characteristic differences in the thermodynamic signatures of tryptophan binding by trp RNA-binding attenuation protein (TRAP) from two different bacterial species. The TRAP 11mer ring binds 11 molecules of tryptophan at symmetry-related sites. Tryptophan binding to Bacillus stearothermophilus TRAP is not cooperative, but isothermal titration calorimetry shows that filling the first tryptophan binding sites of Bacillus subtilis TRAP has a marked effect on the thermodynamics of subsequent ligand binding. We have identified a single, conservative amino acid replacement (Ile to Leu) in B. subtilis TRAP that abolishes this effect, and suggest the initial ligand binding causes a change throughout the wild-type protein ring.
Heddle
Jonathan G
JG
Yokohama City University, Tsurumi, Suehiro 1-7-29, Yokohama 230-0045, Japan. jgh4@tsurumi.yokohama-cu.ac.jp
Okajima
Tomoyuki
T
Scott
David J
DJ
Akashi
Satoko
S
Park
Sam-Yong
SY
Tame
Jeremy R H
JR
D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002151:Calorimetry; D001411:Geobacillus stearothermophilus / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D013816:Thermodynamics; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism
D001426:Bacterial Proteins; C079092:MtrB protein, Bacteria; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D014364:Tryptophan