Active site of trypanothione reductase. A target for rational drug design

TY - JOUR

T1 - Active site of trypanothione reductase. A target for rational drug design

AU - Hunter, William N.

AU - Bailey, Susan

AU - Habash, Jarjis

AU - Harrop, Stephen J.

AU - Helliwell, John R.

AU - Aboagye-Kwarteng, Tamara

AU - Smith, Keith

AU - Fairlamb, Alan H.

N1 - Funding Information: We are extremely grateful to the Wellcome Trust (U.K.) and the National Institutes of Health (U.S.A.) for grants, S.E.R.C Daresbury for synchrotron beam time, the Hasselblad Foundation and the Royal Society for financial support. We thank P. R. Evans, T. A. Jones and J. Spurlino for graphics software, M. Papiz, P. Rizkallah, A. Thompson and C. Nave for assistance and interaction at Daresbury, Z. Derewenda and M. S. Islam for participation in the initial stages of the project, W. Ho1 for his enthusiasm and encouragement, 0. E. Schulz for providing co-ordinates of glutathione complexed with its cognate reductase, K. Douglas, J. Naismith and G. Leonard for discussions and J. Raftery for computing

PY - 1992/9/5

Y1 - 1992/9/5

N2 - The X-ray crystal structure of the enzyme trypanothione reductase, isolated from the trypanosomatid organism Crithidia fasciculata, has been solved by molecular replacement. The search model was the crystal structure of human glutathione reductase that shares approximately 40% sequence identity. The trypanosomal enzyme crystallizes in the tetragonal space group P41 with unit cell lengths of a = 128·9 A ̊ and c = 92·3 A ̊. The asymmetric unit consists of a homodimer of approximate molecular mass 108 kDa. We present the structural detail of the active site as derived from the crystallographic model obtained at an intermediate stage of the analysis using diffraction data to 2·8 Å resolution with an R-factor of 23·2%. This model has root-mean-square deviations from ideal geometry of 0·026 Å for bond lengths and 4·7 ° for bond angles. The trypanosomid enzyme assumes a similar biological function to glutathione reductase and, although similar in topology to human glutathione reductase, has an enlarged active site and a number of amino acid differences, steric and electrostatic, which allows it to process only the unique substrate trypanothione and not glutathione. This protein represents a prime target for chemotherapy of several debilitating tropical diseases caused by protozoan parasites belonging to the genera Trypanosoma and Leishmania. The structural differences between the parasite and host enzymes and their substrates thus provides a rational basis for the design of new drugs active against trypanosomes. In addition, our model explains the results of site-directed mutagenesis experiments, carried out on recombinant trypanothione reductase and glutathione reductases, designed by consideration of the crystal structure of human glutathione reductase.

AB - The X-ray crystal structure of the enzyme trypanothione reductase, isolated from the trypanosomatid organism Crithidia fasciculata, has been solved by molecular replacement. The search model was the crystal structure of human glutathione reductase that shares approximately 40% sequence identity. The trypanosomal enzyme crystallizes in the tetragonal space group P41 with unit cell lengths of a = 128·9 A ̊ and c = 92·3 A ̊. The asymmetric unit consists of a homodimer of approximate molecular mass 108 kDa. We present the structural detail of the active site as derived from the crystallographic model obtained at an intermediate stage of the analysis using diffraction data to 2·8 Å resolution with an R-factor of 23·2%. This model has root-mean-square deviations from ideal geometry of 0·026 Å for bond lengths and 4·7 ° for bond angles. The trypanosomid enzyme assumes a similar biological function to glutathione reductase and, although similar in topology to human glutathione reductase, has an enlarged active site and a number of amino acid differences, steric and electrostatic, which allows it to process only the unique substrate trypanothione and not glutathione. This protein represents a prime target for chemotherapy of several debilitating tropical diseases caused by protozoan parasites belonging to the genera Trypanosoma and Leishmania. The structural differences between the parasite and host enzymes and their substrates thus provides a rational basis for the design of new drugs active against trypanosomes. In addition, our model explains the results of site-directed mutagenesis experiments, carried out on recombinant trypanothione reductase and glutathione reductases, designed by consideration of the crystal structure of human glutathione reductase.

KW - crystal structure

KW - enzyme specificity

KW - glutathione reductase

KW - molecular replacement

KW - trypanothione reductase

UR - https://www.scopus.com/pages/publications/0026760326

U2 - 10.1016/0022-2836(92)90701-K

DO - 10.1016/0022-2836(92)90701-K

M3 - Article

C2 - 1522596

AN - SCOPUS:0026760326

SN - 0022-2836

VL - 227

SP - 322

EP - 333

JO - Journal of Molecular Biology

JF - Journal of Molecular Biology

IS - 1

ER -