Structures of tryparedoxins revealing interaction with trypanothione

BIRGIT HOFMANN,; HEIKE BIEBL,; KARSTEN BRUNS,; GUERRERO, SERGIO ADRIÁN; HENRYK KALISZ,; ULRICH MENGE,; MARISA MONTEMARTINI,; EVERSON NOGOCEKE,; PETER STEINERT,; B. WISSING, JOSEF; LEOPOLD FLOHÉ,; HANS-JÜRGEN HECHT,

BIOLOGICAL CHEMISTRY

Lugar: Alemania; Año: 2001 vol. 382 p. 459 - 471

1431-6730

Structures of tryparedoxins revealing interaction with trypanothione.Hofmann B, Budde H, Bruns K, Guerrero SA, Kalisz HM, Menge U, Montemartini M, Nogoceke E, Steinert P, Wissing JB, Flohe L, Hecht HJ.Department of Biochemistry, Technical University of Braunschweig, Germany.Tryparedoxins (TXNs) catalyse the reduction of peroxiredoxin-type peroxidases by the bis-glutathionyl derivative of spermidine, trypanothione, and are relevant to hydroperoxide detoxification and virulence of trypanosomes. The 3D-structures of the following tryparedoxins are presented: authentic tryparedoxin1 of Crithidia fasciculata, CfTXN1; the his-tagged recombinant protein, CfTXN1H6; reduced and oxidised CfTXN2, and an alternative substrate derivative of the mutein CfTXN2H6-Cys44Ser. Cys41 (Cys40 in TXN1) of the active site motif 40-WCPPCR-45 proved to be the only solvent-exposed redox active residue in CfTXN2. In reduced TXNs, its nucleophilicity is increased by a network of hydrogen bonds. In oxidised TXNs it can be attacked by the thiol of the 1N-glutathionyl residue of trypanothione, as evidenced by the structure of 1N-glutathionylspermidine-derivatised CfTXN2H6-Cys44Ser. Modelling suggests Arg45 (44), Glu73 (72), the Ile110 (109) cis-Pro111 (110)-bond and Arg129 (128) to be involved in the binding of trypanothione to CfTXN2 (CfTXN1). The model of TXN-substrate interaction is consistent with functional characteristics of known and newly designed muteins (CfTXN2H6-Arg129Asp and Glu73Arg) and the 1N-glutathionyl-spermidine binding in the CfTXN2H6-Cys44Ser structure.