FRUITFULL - Molecular Biology

FRUITFULL (FUL) is a MADS-domain transcription factor that plays a major role in the development of the Arabidopsis fruit, the silique. In ful mutants, the silique remains very small and does not open to disperse the seeds.

This is the result of ectopic expression of several genes that are in the wild type repressed by FUL.  In addition to its role in silique development, FUL has been shown to play a role in cauline leaf development and in flowering. Besides being active in these tissues, FUL is also expressed in various other tissues, like the sepals, filaments and roots.

Regulatory network

We are trying to unravel the regulatory networks in which FUL is acting to execute its different functions. This involves the identification of interacting factors at three levels, i) upstream factors that regulate FUL, ii) proteins that are interacting with FUL, and iii) genes that are acting downstream of FUL. We have already performed ChIP-Seq experiments to identify the downstream targets of FUL in the pistil and the silique, and discovered that FUL is regulating a group of growth factors named SAURs (for Small Auxin Up-regulated RNAs). FUL probably represses SAUR genes in the silique, but we also found evidence that FUL is regulating SAUR genes in several other tissues. We are currently investigating the interesting link between FUL and the auxin-regulated SAURs further, and are performing experiments to understand the interplay between both levels of regulation.

Higher order complex formation

MADS-domain transcription factors like FUL are forming higher order complexes with other proteins to regulate transcription. Previous work from the lab (Smaczniak et al., 2012) has shown that MADS proteins can interact with other transcription factors and chromatin remodelers in these complexes. In this project, we would like to further investigate the interaction between MADS proteins and other factors in higher order complexes. We would like to find out how, when and where the specific higher order complexes are formed and which protein motifs are required for the interactions. This work also involves other MADS proteins like APETALA1 (AP1) and SEPALLATA3 (SEP3).

Practical work

  • Functional analyses using T-DNA insertion lines, RNA interference, over-expression, inducible over-expression, CRISPR.
  • Expression analyses using promoter:reporter constructs and real-time RT-PCR (qPCR)
  • Microscopy (Light, CLSM)
  • Protein-protein and protein-DNA interaction assays (Yeast two-hybrid, Yeast one-hybrid, EMSA,  BiFC (split-YFP))