Dr Roman Tuma

Roman Tuma joined the Astbury Center and Institute of Cellular and Molecular Biology as Reader in Biophysics in Sep 2007. He obtained his M.Sc. in biophysics from Charles University, Prague in 1990 and his Ph.D. in Cell Biology and Biophysics from University of Missouri, Kansas City in 1996. After postdoctoral training at the University of Alabama at Birmingham he joined the Institute of Biotechnology, University of Helsinki in 1999 as a group leader. Since 2003 he has been a Research Fellow of the Academy of Finland and his group in Helsinki belongs to the Finnish Centre of Excellence in Virus Research.

Research Areas: Virus, self-assembly, molecular motors, optical tweezers

Research areas: mechanisms and regulation of molecular motors, virus assembly, optical tweezers and spectroscopy, self-assembling nanomachines.

Research projects:

Assembly of dsRNA viruses
Our research is focused on assembly of dsRNA viruses. We have developed in vitro assembly systems for several dsRNA bacteriophages (Cystoviridae family) which are structurally related to viruses of the Reoviridae family (e.g. major pathogens like human rotaviruses). The in vitro systems enabled application of various physico-chemical techniques to study structure, and dynamics of assembly intermediates (Fig. 1).

Mechano-chemical coupling in cooperative molecular motors
Molecular motors convert chemical energy (usually from ATP hydrolysis) into mechanical work. They play essential roles in the replication (helicases) and packaging (packaging motors) of viral genomes (Fig. 2). We are elucidating the principles of coupling between ATP hydrolysis and mechanical motion. i.e. mechano-chemical coupling. We use an interdisciplinary approach based on molecular biology (site-directed mutageneis), structural biology (X-ray crystallography, hydrogen-deuterium exchange), spectroscopy (stopped-flow fluorescence, Raman, IR) and single molecule techniques (tethered particle motion, optical tweezers).

Fig. 2: (A) RNA packaging motor attached to the polymerase complex of dsRNA virus. (B) High-resolution structure of the motor hexamer. (C) ATPase domain (red) exhibits RecA-like fold. Cell. Mol. Life Sci. 63, 1095-1105 (2006).

Bionanoscience and applications

We study the structure and self-assembly of pigments in chlorosomes, bacterial light harvesting antennae. The photosynthetic pigments (bacteriochlorophylls) are organized into lamellar aggregates (Fig. 3). Similar nanostructures can be self-assembled from purified pigments in vitro and exhibit strong excitonic coupling and fast excitation energy transfer rates. These nano-structured assemblies constitute promising biomaterial for photonic applications and photovoltaic cells.

The results of our basic research on molecular motors are exploited in the design of active nanopores and novel molecular motor-based machines that can transport, detect and process nucleic acids (Fig. 4).