Redox modulation of plant developmental regulators from the class I TCP transcription factor family

VIOLA, IVANA L.; GÜTTLEIN, LEANDRO N.; GONZALEZ, DANIEL H.

PLANT PHYSIOLOGY.

AMER SOC PLANT BIOLOGISTS

Lugar: Rockville; Año: 2013 vol. 162 p. 1434 - 1447

0032-0889

TCP (TEOSINTE BRANCHED1-CYCLOIDEA-PCF) transcription factors participate in plant developmental processes associated with cell proliferation and growth. Most members of class I, one of the two classes that compose the family, have a conserved Cys at position 20 of the TCP DNA binding and dimerization domain. We show that Arabidopsis thaliana class I proteins with Cys20 are sensitive to redox conditions, since their DNA binding activity is inhibited after incubation with the oxidants diamide, oxidized glutathione or H2O2, or with NO producing agents. Inhibition can be reversed by treatment with the reductants dithiothreitol or reduced glutathione, or incubation with the thioredoxin/thioredoxin reductase system. Mutation of Cys20 in the class I protein TCP15 abolished its redox sensitivity. Under oxidizing conditions, covalently linked dimers were formed, suggesting that inactivation is associated with the formation of intermolecular disulfide bonds. Inhibition of class I TCP protein activity was also observed in vivo, in yeast cells expressing TCP proteins and in plants after treatment with redox agents. This inhibition was correlated with modifications in the expression of the downstream CUC1 gene in plants. Modeling studies indicated that Cys20 is located at the dimer interface near the DNA binding surface. This places this residue in the correct orientation for intermolecular disulfide bond formation and explains the sensitivity of DNA binding to oxidation of Cys20. The redox properties of Cys20 and the observed effect of cellular redox agents both in vitro and in vivo suggest that class I TCP protein action is under redox control in plants.