2TIR

CRYSTAL STRUCTURE ANALYSIS OF A MUTANT ESCHERICHIA COLI THIOREDOXIN IN WHICH LYSINE 36 IS REPLACED BY GLUTAMIC ACID

Summary for 2TIR

• Entry DOI: 10.2210/pdb2tir/pdb
• Descriptor: THIOREDOXIN, COPPER (II) ION (3 entities in total)
• Functional Keywords: electron transport
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 11750.87

Authors

Nikkola, M.,Gleason, F.K.,Fuchs, J.A.,Eklund, H. (deposition date: 1993-01-10, release date: 1993-10-31, Last modification date: 2024-10-23)

Primary citation

Nikkola, M.,Gleason, F.K.,Fuchs, J.A.,Eklund, H.
Crystal structure analysis of a mutant Escherichia coli thioredoxin in which lysine 36 is replaced by glutamic acid.
Biochemistry, 32:5093-5098, 1993

PubMed Abstract: The structure of a mutant Escherichia coli thioredoxin with a glutamic acid substituted for a conserved lysine at position 36 adjacent to the active site has been solved using molecular replacement and refined at 2.0-A resolution to a crystallographic residual of 19.9%. The mutant was crystallized in an orthorhombic space group with one molecule in the asymmetric unit. The structure of the mutant thioredoxin shows overall good agreement with the wild-type E. coli thioredoxin. The root-mean-square deviations for all C alpha s are 0.45 and 0.79 A between the mutant structure and the two molecules in the asymmetric unit of the wild-type crystals. Structural changes are seen in several residues in the active-site region preceding the disulfide. A reverse turn of residues 29-32 changes the conformation from a type I to a type II turn. This change may be related to the loss of a hydrogen bond from Lys-36 to the main-chain carbonyl of residue 30 due to the mutation. The C alpha atom of Trp-31 has moved 1.9 A and the indole ring no longer makes hydrogen bonds to the carboxyl group of Asp-61 but instead participates in a crystal contact. The structural differences seen in the mutant thioredoxin may be influenced by the crystal packing. The substituted Glu-36 makes extensive crystal contacts. The static fluorescence of this mutant thioredoxin has a different pH dependence than the wild type.

PubMed: 8098620
DOI: 10.1021/bi00070a017

Experimental method

X-RAY DIFFRACTION (2 Å)