2OQX image
Entry Detail
PDB ID:
2OQX
Keywords:
Title:
Crystal Structure of the apo form of E. coli tryptophanase at 1.9 A resolution
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2007-02-01
Release Date:
2007-02-20
Method Details:
Experimental Method:
Resolution:
1.90 Å
R-Value Free:
0.23
R-Value Work:
0.20
R-Value Observed:
0.21
Space Group:
F 2 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Tryptophanase
Chain IDs:A
Chain Length:467
Number of Molecules:1
Biological Source:Escherichia coli
Modified Residue
Compound ID Chain ID Parent Comp ID Details 2D Image
CME A CYS S,S-(2-HYDROXYETHYL)THIOCYSTEINE
Primary Citation
The structure of apo tryptophanase from Escherichia coli reveals a wide-open conformation.
Acta Crystallogr.,Sect.D 63 969 974 (2007)
PMID: 17704565 DOI: 10.1107/S0907444907036396

Abstact

The crystal structure of apo tryptophanase from Escherichia coli (space group F222, unit-cell parameters a = 118.4, b = 120.1, c = 171.2 A) was determined at 1.9 A resolution using the molecular-replacement method and refined to an R factor of 20.3% (R(free) = 23.2%). The structure revealed a significant shift in the relative orientation of the domains compared with both the holo form of Proteus vulgaris tryptophanase and with another crystal structure of apo E. coli tryptophanase, reflecting the internal flexibility of the molecule. Domain shifts were previously observed in tryptophanase and in the closely related enzyme tyrosine phenol-lyase, with the holo form found in an open conformation and the apo form in either an open or a closed conformation. Here, a wide-open conformation of the apo form of tryptophanase is reported. A conformational change is also observed in loop 297-303. The structure contains a hydrated Mg(2+) at the cation-binding site and a Cl(-) ion at the subunit interface. The enzyme activity depends on the nature of the bound cation, with smaller ions serving as inhibitors. It is hypothesized that this effect arises from variations of the coordination geometry of the bound cation.

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