3ZO8: Wild-type Chorismate Mutase Of Bacillus Subtilis At 1.6 A Resolution

Citation:
Abstract
For more than half a century, transition state theory has provided a useful framework for understanding the origins of enzyme catalysis. As proposed by Pauling, enzymes accelerate chemical reactions by binding transition states tighter than substrates, thereby lowering the activation energy compared with that of the corresponding uncatalyzed process. This paradigm has been challenged for chorismate mutase (CM), a well-characterized metabolic enzyme that catalyzes the rearrangement of chorismate to prephenate. Calculations have predicted the decisive factor in CM catalysis to be ground state destabilization rather than transition state stabilization. Using X-ray crystallography, we show, in contrast, that a sluggish variant of Bacillus subtilis CM, in which a cationic active-site arginine was replaced by a neutral citrulline, is a poor catalyst even though it effectively preorganizes chorismate for the reaction. A series of high-resolution molecular snapshots of the reaction coordinate, including the apo enzyme, and complexes with substrate, transition state analog and product, demonstrate that an active site, which is only complementary in shape to a reactive substrate conformer, is insufficient for effective catalysis. Instead, as with other enzymes, electrostatic stabilization of the CM transition state appears to be crucial for achieving high reaction rates.
PDB ID: 3ZO8Download
MMDB ID: 119140
PDB Deposition Date: 2013/2/20
Updated in MMDB: 2014/12
Experimental Method:
x-ray diffraction
Resolution: 1.59  Å
Source Organism:
Similar Structures:
Biological Unit for 3ZO8: trimeric; determined by author and by software (PISA)
Molecular Components in 3ZO8
Label Count Molecule
Proteins (3 molecules)
3
Chorismate Mutase Aroh(Gene symbol: aroH)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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