Budweis Single-Molecule Group
Our research group is taking the advantage of living on the border between biology and physics. We are mostly focused on single-molecule research and we are currently looking for motivated students of all degrees!
Right now we are looking for motivated students of all levels (Bc, Mgr, PhD)!
Building C (room 01037)
Faculty of Science
University of South Bohemia in České Budějovice
370 05 České Budějovice
GPS: 48.9772847N, 14.4451364E
Allosteric communication in membrane protein complexes linked to conformational transitions on multiple timescales
- Development of novel mechanistic models of molecular machines behind protein translocation
Allosterically modulated molecular machines mediate many of the key processes in all forms of life. The Sec translocon, a membrane bound protein complex, is the principal route for the efficient transport of heterogeneous polypeptides across or into lipid bilayers. The bacterial translocon consists of two main parts, a cytosolic ATPase SecA and membrane channel SecYEG. Based on our group’s recent findings we propose that the Sec translocon is a novel type of stochastically coupled hybrid molecular machine, where the processive SecA steers the energy landscape of a stochastic SecYEG channel allosterically dependent on nucleotide state. We present a number of research projects to map the full allosteric network regulating different stages of protein translocation in the Sec complex using a combination of mutagenesis, single-molecule and in silico methods.
• Allen, W. J., et al (2016) Two-way communication between SecY and SecA suggests a Brownian ratchet mechanism for protein translocation, Elife. 5.
• Fessl, T., et al (2018) Dynamic action of the Sec machinery during initiation, protein translocation and termination, Elife. 7.
• Corey, R. A., et al (2019) ATP-induced asymmetric pre-protein folding as a driver of protein translocation through the Sec machinery, Elife. 8.
• Fessl, T., et al (2020) Dynamics of Membrane Proteins Monitored by Single-Molecule Fluorescence Across Multiple Timescales, Methods in Molecular Biology
Studies of G protein signaling at the single molecule level
- Getting insights into non-canonical G protein signaling and development of signaling activity sensors
The G protein signaling cascade is a major pathway responsible for cellular communication with the external environment. It is present in all eukaryotes from yeast to humans. G proteins transduce signals from a variety of chemical and physical stimuli including hormones, odorants, neurotransmitters, and light. Up to 50% of all modern prescription drugs target this signaling cascade. However, many aspects of G protein signaling remain unclear. Our goal is to gain insights into non-conventional properties of G protein signaling in mammalian and fungal cells. Particularly, we are interested in precoupling between G proteins and G protein-coupled receptors (GPCRs), dimerization and heteromerization of GPCSs, and development of signaling activity sensors (1-5). In our research we use advanced imaging techniques, including single-molecule imaging, combined with molecular biology, cell biology methods and advanced data processing. We strive to utilize cutting-edge techniques and multidisciplinary approaches to do excellent science.
Figure 1. Outstanding questions in G protein signaling research
Figure 2. A snapshot of real time dual channel single-molecule imaging of interactions between G proteins and G protein-coupled receptors in a live cell
- A. Bondar, J. Lazar, Optical sensors of heterotrimeric G protein signaling. FEBS J 288, 2570-2584 (2021).
- A. Bondar, O. Rybakova, J. Melcr, J. Dohnalek, P. Khoroshyy, O. Tichacek, S. Timr, P. Miclea, A. Sakhi, V. Markova, J. Lazar Quantitative Linear Dichroism Imaging of Molecular Processes in Living Cells Made Simple by Open Software Tools Communications Biology 4, 189 (2021).
- A. Bondar, W. Jang, E. Sviridova, N. A. Lambert, Components of the Gs signaling cascade exhibit distinct changes in mobility and membrane domain localization upon beta2-adrenergic receptor activation. Traffic 21, 324-332 (2020).
- A. Bondar, J. Lazar, The G protein Gi1 exhibits basal coupling but not preassembly with G protein-coupled receptors. J Biol Chem 292, 9690-9698 (2017).
- A. Bondar, J. Lazar, Dissociated GalphaGTP and Gbetagamma protein subunits are the major activated form of heterotrimeric Gi/o proteins. J Biol Chem 289, 1271-1281 (2014).