DNA BINDING PROPERTIES OF THE ARABIDOPSIS ATTCP11 TRANSCRIPTION FACTOR. THE ROLE OF Thr15

IVANA VIOLA; RODRIGO RIPOLL; 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

TCP transcription factors are regulators of plant cell growth andproliferation. This proteins contain the TCP domain that ispredicted to form a non-canonical basic helix-loop-helix (bHLH)structure required for DNA binding and dimerization. TCP proteinsare divided into two classes and bind DNA sequences that differfrom the consensus binding sites of other bHLH. To gain insightinto the DNA binding properties and functions of class I TCPtranscription factors from Arabidopsis, we have examined theinteraction of three of these factors with DNA. SELEXexperiments performed with TCP15 and TCP20 indicated thatthese proteins have similar, though not identical, DNA bindingpreferences and are able to interact with non-palindromic bindingsites of the type GTGGGNCCNN. TCP11 shows a different DNAbinding specificity, with a preference for the sequenceGTGGGCCNNN. The distinct DNA binding properties of TCP11are due to the presence of Thr at position 15 of the TCP domain, aposition that is occupied by Arg in other TCP proteins. In addition,TCP11 forms heterodimers with TCP15 that have increased DNAbinding efficiency and are able to interact with DNA sequencesbound only poorly by the respective homodimers. The resultssuggest that changes in DNA binding preferences may be one of themechanisms through which class I TCP proteins achieve functionalspecificity.