2EXT: Trap4 (Engineered Trap)

The protein TRAP (trp RNA binding attenuation protein) forms a highly thermostable ring-shaped 11-mer. By linking in tandem two, three, or four DNA sequences encoding TRAP monomers, we have engineered new rings that consist of 12 TRAP subunits and bind 12 ligand molecules. The hydrogen bonding pattern and buried surface area within and between subunits are essentially identical between the 11-mer and 12-mer crystal structures. Why do the artificial proteins choose to make single 12-mer rings? The 12-mer rings are highly sterically strained by their peptide linkers and far from thermostable. That proteins choose to adopt a strained conformation of few subunits rather than an unstrained one with 11 subunits demonstrates the importance of entropic factors in controlling protein-protein interactions in general.
PDB ID: 2EXTDownload
MMDB ID: 40385
PDB Deposition Date: 2005/11/8
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 2EXT: dodecameric; determined by author and by software (PISA,PQS)
Molecular Components in 2EXT
Label Count Molecule
Proteins (12 molecules)
Transcription Attenuation Protein Mtrb
Molecule annotation
Chemicals (12 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB