Evolutionary Developmental Biology (Evo-Devo)
Kim, Sangtae , Kaufmann, Kerstin , Theißen, Güenter , Soltis, Pamela S. , Soltis, Douglas E. .
Protein-protein interactions of B-class MADS-box homologues in Amborella trichopoda (Amborellaceae).
INTERACTIONS between proteins are essential for their function and for the biological processes they control. In the ABC model of floral organ identity, B-class MADS-box genes determine petal and stamen identities. In the eudicot Arabidopsis, heterodimerization of AP3 and PI is essential, and tetramer formation of protein subunits with other MADS-box proteins has been hypothesized. In the monocot Lilium, PI/PI homodimerization is also possible, in addition to heterodimerization, indicating that not all angiosperms have the same multimer requirements as Arabidopsis. Certain amino acid residues located in the K1 subdomain of B-class MADS-box proteins in Arabidopsis are crucial for their heterodimerization. We have reported that these residues were strongly conserved across all angiosperms except Amborella trichopoda, the putative sister-group to all other extant angiosperms and further that there is a striking similarity in the multimer-signaling C domains of the Amborella B-class proteins. We hypothesized that the unique structural features of Amborella protein subunits may confer a greater range of possible multimer combinations for proteins in Amborella than in eudicots or monocots. This greater potential for tetramer variation in Amborella may result in a flexible mode of B-gene function, perhaps an important factor in the early stages of angiosperm evolution. To test the hypothesis of greater flexibility in multimer formation in Amborella, we performed yeast 2- and 3-hybridization experiments for Amborella B-class proteins and other MADS-box proteins. In our preliminary analyses, an AP3-1/AP3-1 homodimer was detected in addition to AP3-1/AP3-2, AP3-1/PI, and AP3-2/PI heterodimers. Our data suggest greater flexibility of MADS-box protein interactions in basal angiosperms; this flexibility could be associated with floral variation in basal lineages of flowering plants.
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1 - University of Florida, Department of Botany, 220 Bartram Hall, P.O. Box 118526, Gainesville, Florida, 32611-8526, USA
2 - Fridrich-Schiller-Universität Jena, Lehrstuhl fűr Genetik, Philosophenweg 12, Jena, D-07743, Germany
3 - University of Florida, Department of Botany, Florida Museum of Natural History, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
Presentation Type: Oral Paper:Papers for Topics
Location: 303/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 2:45 PM