R E D O X R E G U L AT I O N O F C L A S S I T C P TRANSCRIPTION FACTORS FROM Arabidopsis thaliana

LEANDRO GÜTTLEIN; IVANA VIOLA; DANIEL GONZALEZ

Puerto Madryn

Congreso; XLVI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The TCP domain is a conserved domain present only in planttranscription factors. It contains a basic region followed by a helixloop-helix motif that resembles the bHLH domain. Phylogeneticstudies showed that there are two major classes of TCP domains anda consensus sequence for each class has been derived. Class Iproteins contain a highly conserved Cys residue in helix I. In thisstudy we evaluated the effect of redox agents on the DNA bindingcapacity and quaternary structure of members of the class I TCPfamily from A. thaliana. Our assays show that DTT, GSH orthioredoxin treatments increase the DNA binding efficiency ofthree different class I proteins, while the oxidation with diamide,H O or GSSG prevents the interaction with DNA. For TCP20 and 2 2TCP21, this is due to the formation of intermolecular disulfidebonds. TCP15 is inactivated by GSSG without a change inelectrophoretic mobility, suggesting that it may be glutathionylatedunder these conditions. The DNA binding activity of TCP4, a classII protein, and of TCP16 (a class I protein that lacks the conservedCys) is not affected by redox agents. The results presented in thiswork constitute the first report of a redox regulation of TCPtranscription factors. These modifications may act to regulate theactivity of class I factors according to the redox conditions of plantcells.