Opening Image: Ribbon model of TRAP 11-mer complexed with single-stranded RNA. The 11 L-Trp molecules are shown in spacefill.
TRAP contains 11 identical subunits. spacefilled model of TRAP, viewed along 11-fold symmetry axis.
TRAP binds 11 tryptophan molecules in a highly cooperative manner. The binding sites for tryptophan are at the subunit interfaces. Binding induces a conformation change that completely entraps the tryptophan ligands. RNA binding occurs after tryptophan binding.
The protein is colored cyan, and the tryptophan molecules are shown in CPK colors.
cartoon model of protein. The connecting loops are shown in white.
The crystal structure of the attenuation protein was determined with a 53-base single stranded RNA containing eleven GAG triplets separated by AU dinucleotides.
GAU GAG AU GAG AU GAG AU GAG
AU GAG AU GAG AU GAG AU GAG
AU GAG AU GAG AU GA
The RNA is shown in spacefill. cartoon rendering.
GAG triplets. Compare the conformations of the bound triplets.
protein, colored in cyan.