The group has left the department and has moved to Adelphi University.
The plant hormone cytokinin plays an important role in many physiological and developmental processes as well as the reaction of plants to abiotic and biotic stress. The cytokinin signal perception and transduction is mediated by a multi-step phospho-relay system, a variation of the classical two-component signaling pathway found in bacteria (Heyl and Schmülling, 2003).
In the current model of this signaling pathway, the binding of cytokinin to the ligand binding domain, the CHASE domain, causes the mainly ER-localized cytokinin receptor histidine kinase (HK) to auto-phosphorylate itself at a conserved histidine residue (Heyl et al., 2007; Wulfetange et al., 2011). Subsequently this signal is transferred within the receptor protein to a canonical aspartate residue of a C-terminal response regulator domain. Afterwards, the phosphoryl signal is transferred to a histidine phospho-transfer protein (HPt), which can translocate to the nucleus, where it activates the type-B response regulators (type-B RRs) by phosphorylation of the response regulator domain (Dortay et al., 2006). These Myb- transcription factors activate the transcription of their target genes, one group of which are the type-A RRs (Heyl et al., 2008). These regulate in a negative feedback loop the activity of cytokinin signaling and represent an internode, linking the cytokinin signaling pathway with other cellular signaling pathways (Gruhn and Heyl, 2013).
In the Heyl group we are interested to understand the molecular mechanism of the cytokinin signaling system. Towards this goal we currently focus on two areas, the regulation of the transcriptional response to cytokinin and the evolution of the cytokinin signal transduction.