2G7B: Crystal Structure Of The R132k:r111l:l121e Mutant Of Cellular Retinoic Acid Binding Protein Type Ii In Complex With All-trans-retinal At 1.18 Angstroms Resolution

Rational redesign of the binding pocket of Cellular Retinoic Acid Binding Protein II (CRABPII) has provided a mutant that can bind retinal as a protonated Schiff base, mimicking the binding observed in rhodopsin. The reengineering was accomplished through a series of choreographed manipulations to ultimately orient the reactive species (the epsilon-amino group of Lys132 and the carbonyl of retinal) in the proper geometry for imine formation. The guiding principle was to achieve the appropriate Burgi-Dunitz trajectory for the reaction to ensue. Through crystallographic analysis of protein mutants incapable of forming the requisite Schiff base, a highly ordered water molecule was identified as a key culprit in orienting retinal in a nonconstructive manner. Removal of the ordered water, along with placing reinforcing mutations to favor the desired orientation of retinal, led to a triple mutant CRABPII protein capable of nanomolar binding of retinal as a protonated Schiff base. The high-resolution crystal structure of all-trans-retinal bound to the CRABPII triple mutant (1.2 A resolution) unequivocally illustrates the imine formed between retinal and the protein.
PDB ID: 2G7BDownload
MMDB ID: 45458
PDB Deposition Date: 2006/2/27
Updated in MMDB: 2017/10
Experimental Method:
x-ray diffraction
Resolution: 1.18  Å
Source Organism:
Similar Structures:
Biological Unit for 2G7B: monomeric; determined by author
Molecular Components in 2G7B
Label Count Molecule
Protein (1 molecule)
Cellular Retinoic Acid-binding Protein 2(Gene symbol: CRABP2)
Molecule annotation
Chemicals (3 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB