Currently we are working on the following topics:

Nutrient sensing in plants

How do plant K+ channels sense K+?

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Projects

Functional regulation of plant ion channels

Assembly

Ion channels are mostly multimeric proteins. We are investigating the assembly of these proteins by using diverse methods in vitro and in vivo [1-6]. The model system for these studies are voltage-gated plant potassium channels. Functional channels of this type are built of 4 a-subunits. In 1997 [1] it was proposed that different a-subunits can form hetermeric K+ channels. However, it was not clear whether plants make use of the “heteromerization potential” to increase the diversity of functional K+ channels in a cell. Recently, we could unequivocally proof the existence of heteromeric K+ channels in plants by combining biophysical, mathematical and plant physiological methods [5]. These results may now explain, why some in vivo plant K+ channels differ in their features when compared with heterologously expressed plant K+ channels [7]. Reference [8] summarizes the findings on the assembly of plant K+ channels.

Gating of plant K+ channels

Voltage-gated K+ channels of plants show an astonishing diversity at the functional level. They segregate into 4 groups: (i) inward-rectifying (Kin) channels allow the potassium uptake, (ii) outward-rectifying (Kout) channels allow the potassium release, (iii) weak-rectifying (Kweak) channels allow both, K+ uptake and release, and (iv) silent (Ksilent) potassium channel a-subunits do not form functional channels on their own [9].

In recent studies we could clarify that Kweak channels are in fact specialized Kin channels that react very sensitively towards post-translational modifications [10-12]. Currently, we are exploring the physiological consequences of this regulation in transgenic plants.

Kout channels are characterized by the unique characteristic that they are able to sense the external K+ concentration. They adjust their activity accordingly in order to guarantee that potassium ions are transported only in one direction: out of the cell. The mechanism of this K+-sensing phenomenon could recently be uncovered [13]. It turned out that the K+-sensing mechanism is tightly bound to the voltage-gating of this channel (see above “Nutrient sensing in plants”). This finding might be the key to understand the different voltage-gating of Kin and Kout channels.  In the past and in ongoing studies we are generating chimeras between the Kin channel KAT1 and the Kout channel SKOR [14]. These experimental studies are flanked by computational simulations of the channel structure.

Dynamics of artificial and natural gene-regulatory networks

Another topic of interest of the group is the analysis of the dynamics of gene-regulatory networks [15-17]. Currently, we are designing artificial gene-regulatory networks in eukaryotic cells. The goal is to create cells that react with a special answer to different external stimuli.

… interested? Do not hesitate to contact us or to join us …

We are very open for national and international collaborations.

At the moment we are collaborating with partners from
Colombia, Chile, France, Germany, Italy, Japan, and the UK.

Interested to work in a “global” environment?

Ţ Welcome! Bienvenue! Bienvenidos! Benvenuto! Willkommen!

Heisenberg-Group of Biophysics and Molecular Plant Biology

References (details on the page “Publications”)

[1] Dreyer et al., 1997, Biophys. J. 72:2143-2150; [2] Ache et al., 2001, Plant J. 27:571-580; [3] Dreyer et al., 2004, Biophys. J. 87:858-872; [4] Xicluna et al., 2007, J. Biol. Chem. 282:486-494; [5] Lebaudy et al., 2008a, Plant J. in press; [6] Lebaudy et al., 2008b, PNAS 105:5271-5276; [7] Brüggemann et al., 1999a, PNAS 96:3298-3302; [8] Jeanguenin et al., 2008, Plant Signal Behav 3:9 in press; [9] Dreyer et al., 2004a, In Membrane Transport in Plants, Blatt M.R. (ed). pp 150-192. Oxford, Blackwell; [10] Dreyer et al., 1998, FEBS Lett. 430:370-376; [11] Michard et al., 2005a, Plant J. 44:783-797; [12] Michard et al., 2005b, J. Gen. Physiol. 126:605-617; [13] Johansson et al., 2006, Plant J. 46:269-281; [14] Porée et al., 2005, Biochem.Biophys.Res.Commun. 332:465-472; [15] Riańo-Pachón et al., 2005, Plant J. 43:205-212; [16] Riańo-Pachón et al., 2007, BMC Bioinformatics 8:42; [17] Gómez-Porras et al., 2007, BMC Genomics 8:260.