title: Toward an interaction map of the two-component signaling pathway of Arabidopsis thaliana.
abstract: Among the signal transduction pathways in higher eukaryotes, the two-component system (TCS) is unique to plants. In the model plant Arabidopsis thaliana, it consists of more than 30 proteins, including eight receptors, five phosphotransmitters and 23 response regulators. One of its important functions is to perceive and transduce the signal of the plant hormone cytokinin. The basic signal flow within the TCS is well-understood, but it is unclear how this pathway is integrated with the remainder of the proteome. Thus, knowledge about the interactions of TCS proteins should contribute to the understanding of their mode of action. Therefore, we conducted medium-scale yeast two-hybrid screens focusing on those members of the TCS, which are thought to be involved in cytokinin signaling. In total, more than 6.3 x 10 (7) transformants were screened resulting in the identification of 160 different interactions, of which 136 were novel. Most of the interacting proteins belong to the functional categories of signal transduction and protein metabolism. TCS proteins and their interactors localized to the same subcellular compartment in many cases, a prerequisite to being of biological relevance. The resulting interaction network map revealed large differences in the connectivity. Cytokinin receptors (AHK2, CRE1/AHK4) showed the highest numbers of different interaction partners. This study is the first systematic protein-protein interaction experiment for a plant signal system and provides numerous starting points for further analysis of the molecular mechanisms used to convert the signal carried by the TCS into biological processes.
authors.affiliation: Institute of Biology/Applied Genetics, Free University of Berlin, Albrecht-Thaer-Weg 6, 14195 Berlin, Germany.
authors.forename: Hakan
authors.initials: H
authors.lastname: Dortay
authors.forename: Nijuscha
authors.initials: N
authors.lastname: Gruhn
authors.forename: Andreas
authors.initials: A
authors.lastname: Pfeifer
authors.forename: Mareike
authors.initials: M
authors.lastname: Schwerdtner
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmülling
authors.forename: Alexander
authors.initials: A
authors.lastname: Heyl
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary; D015203:Reproducibility of Results; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D017931:DNA Primers; D018076:DNA, Complementary