PDBsum entry 1kfe

Lyase

PDB id: 1kfe

Contents

Protein chains

252 a.a. *

394 a.a. *

Ligands

PLS

Metals

_NA

Waters ×506

* Residue conservation analysis

PDB id:

1kfe

Name:

Lyase

Title:

Crystal structure of alphat183v mutant of tryptophan synthase from salmonella typhimurium with l-ser bound to the beta site

Structure:

Tryptophan synthase alpha chain. Chain: a. Synonym: trpa. Engineered: yes. Mutation: yes. Tryptophan synthase beta chain. Chain: b. Engineered: yes

Source:

Salmonella typhimurium. Organism_taxid: 602. Expressed in: escherichia coli. Expression_system_taxid: 562. Organism_taxid: 99287. Strain: lt2.

Biol. unit:

Tetramer (from PDB file)

Resolution:

1.75Å R-factor: 0.192 R-free: 0.225

Authors:

V.Kulik,M.Weyand,R.Siedel,D.Niks,D.Arac,M.F.Dunn,I.Schlichting

Key ref:

V.Kulik et al. (2002). On the role of alphaThr183 in the allosteric regulation and catalytic mechanism of tryptophan synthase. J Mol Biol, 324, 677-690. PubMed id: 12460570 DOI: 10.1016/S0022-2836(02)01109-9

Date:

20-Nov-01 Release date: 07-Jan-03

Protein chain

P00929  (TRPA_SALTY) -  Tryptophan synthase alpha chain from Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)

Seq: 268 a.a.

Struc: 252 a.a.*

Protein chain

P0A2K1  (TRPB_SALTY) -  Tryptophan synthase beta chain from Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)

Seq: 397 a.a.

Struc: 394 a.a.

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: Chains A, B: E.C.4.2.1.20 - tryptophan synthase.
• Pathway: Tryptophan Biosynthesis
• Reaction: (1S,2R)-1-C-(indol-3-yl)glycerol 3-phosphate + L-serine = D-glyceraldehyde 3-phosphate + L-tryptophan + H2O
• Cofactor: Pyridoxal 5'-phosphate

Pyridoxal 5'-phosphate (Bound ligand (Het Group name = PLS) matches with 65.22% similarity)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1016/S0022-2836(02)01109-9

J Mol Biol 324:677-690 (2002)

PubMed id: 12460570

On the role of alphaThr183 in the allosteric regulation and catalytic mechanism of tryptophan synthase.

V.Kulik, M.Weyand, R.Seidel, D.Niks, D.Arac, M.F.Dunn, I.Schlichting.

ABSTRACT

The catalytic activity and substrate channeling of the pyridoxal 5'-phosphate-dependent tryptophan synthase alpha(2)beta(2) complex is regulated by allosteric interactions that modulate the switching of the enzyme between open, low activity and closed, high activity states during the catalytic cycle. The highly conserved alphaThr183 residue is part of loop alphaL6 and is located next to the alpha-active site and forms part of the alpha-beta subunit interface. The role of the interactions of alphaThr183 in alpha-site catalysis and allosteric regulation was investigated by analyzing the kinetics and crystal structures of the isosteric mutant alphaThr183Val. The mutant displays strongly impaired allosteric alpha-beta communication, and the catalytic activity of the alpha-reaction is reduced one hundred fold, whereas the beta-activity is not affected. The structural work establishes that the basis for the missing inter-subunit signaling is the lack of loop alphaL6 closure even in the presence of the alpha-subunit ligands, 3-indolyl-D-glycerol 3'-phosphate, or 3-indolylpropanol 3'-phosphate. The structural basis for the reduced alpha-activity has its origins in the missing hydrogen bond between alphaThr183 and the catalytic residue, alphaAsp60.

Selected figure(s)

Figure 7.
Figure 7. SigmaA-weighted 2Fo 2 Fc electron density maps contoured at 1s around the external aldimine bLys87 in aT183VSer. The Schiff-base linkage between PLP and bLys87 is broken. As can be seen from Figure 8, bLys87 interacts with the phosphoryl group of PLP. The Figure was prepared using ``BOBSCRIPT'', 41 MOLS- CRIPT 39 and RASTER3D. 40

The above figure is reprinted by permission from Elsevier: J Mol Biol (2002, 324, 677-690) copyright 2002.

Figure was selected by an automated process.