ROLES OF ABI5/ABF BINDING PROTEINS (AFPS) IN MODULATING THE ABSCISIC ACID CORE SIGNALING PATHWAY
Lynch, T.J., Erickson, B.J., Pham, V., Losic, T., Morales, A. and Finkelstein R.R.
Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, USA
Contact: Ruth Finkelstein, firstname.lastname@example.org
Several Abscisic Acid-Insensitive(ABI)5/ABRE Binding Factor(ABF) binding proteins (AFPs) inhibit ABA response, resulting in extreme ABA resistance and failure to complete maturation in seeds of transgenic Arabidopsis overexpression lines. Annotated only as proteins with domains of unknown functions, numerous roles have been proposed for these proteins. These include inhibiting function of the transcription factors that they bind by promoting their proteasomal degradation and by altering expression of ABA-regulated genes through interactions with chromatin modifiers such as histone deacetylases and the TOPLESS family of co-repressors. We have identified additional interactions with many components of the ABA core signaling pathway and are testing the functional significance of all of these interactions genetically and biochemically. The AFPs are predicted to be intrinsically unstructured proteins and we propose that they act as scaffolds for multiple protein complexes affecting ABA and stress response.