Our research focus is to understand how cellular signaling in plants is orchestrated on the cellular level. Specifically, we are investigating the function of receptor proteins, specifically receptor-like protein kinases, and how they control cellular signaling events at the plasma membrane and how RLKs participate in reactive oxygen species (ROS)-mediated signal transduction. As a tool we use the model plant species Arabidopsis thaliana. On the more theoretical side we are interested in the physiological significance of protein family expansion in various plants and non-plant organisms. We are part of the Institute of Plant Molecular Biology at the Biology Centre CAS in České Budějovice. A part of the team continues to work at the University of Helsinki, Viikki Plant Science Centre (ViPS) in Finland.
The cysteine-rich receptor-like kinases (CRKs)
The CRKs and the related cysteine-rich receptor-like proteins (CRRSPs) are groups of receptor-proteins. They are encoded by large gene families in higher plants. We are analyzing the biochemical and physiological roles of the CRKs as well as their molecular function. The work was initiated in the ERA-PG consortium “PROSIG”. Together with the consortium we have generated a comprehensive knockout collection for all CRKs (Bourdais et al., 2015). Now, on this foundation we are busy understanding the molecular biology and biochemistry of the CRKs.
We currently focus on the role of CRKs which belong to the highly conserved “basal group” of CRKs. In particular CRK2 has important roles in the responses to biotic and abiotic environmental stimuli (Hunter et al., 2019; Kimura et al., 2020).
Organization of signaling events and signal integration at the plasma membrane
Numerous signals are converging on plasma membrane-localized enzymes including protein phosphorylation, calcium, phosphatidic acid, G-proteins, protein-protein interactions (Kimura et al., 2017). Starting from our interest in the CRKs, we are now investigating how those signaling events are prioritized and integrated at the plasma membrane. Since CRKs can interact with plant homologs of NADPH oxidases, RBOHs, we use RBOHD as model system to dissect all the signals that converge on the enzyme and regulate the active production of ROS into the apoplastic space (Castro et al., 2021). We follow signaling from the plasma membrane through different protein complexes into the nucleus where changes in transcription factor protein complexes determine transcriptional regulation in response to a stimulus.
Gene family expansion in plants
We are interested in the underlying reasons for gene family expansions in plants. In the most general sense we are asking why many gene families in higher plants have expanded considerably compared to animals and other organisms. With this idea in mind we have analyzed the evolution of CRKs and CRRSPs (Vaattovaara et al., 2019) and now use this information in our wet lab work investigating the molecular roles of the CRKs.