Abstract:
Molecular machinery that governs bacterial motility (chemotaxis) is one of the best studied
signal transduction systems in Nature. Sophisticated behavior of Earth’s smallest organisms
fascinated naturalists of the last century as well as modern molecular biologists, who hoped
that the properties of the underlying molecular navigation system in bacteria would resemble
those of higher organisms. However, the latest structural and functional studies revealed no
such similarity in the molecular design. Using the wealth of information encoded in hundreds
of bacterial genomes and a variety of bioinformatics tools we reconstructed the natural history
of this system. Here we show that the chemotaxis system is the evolutionary youngest and
most sophisticated signal transduction pathway in prokaryotes. It appeared in Bacteria after the
separation of the three domains of Life and has been later transferred into Archaea, but not into
Eucarya. It developed gradually from the simplest signal transduction systems comprised of a
single protein with sensory and regulatory capabilities. The chemotaxis system differentiated
into several functional classes that evolved to control not only motility, but also other cellular
functions. Detailed computational analysis of individual system components allowed us to reveal
novel structural and functional insights that have not been identified by previous experimental
studies.
Speaker bio:
Igor B. Zhulin is a Distinguished Scientist at the Computing and Computational Sciences
Directorate of the Oak Ridge National Laboratory and a Joint Faculty Professor at the
Department of Microbiology, University of Tennessee. He received his B.Sc. degree in
Biology from Saratov State University and his Ph.D. in Microbiology from St. Petersburg State
University. During his postdoctoral studies he transitioned from experimental to computational
biology. He is an editor of “Computational Biology” and “Genomics and Proteomics” sections of
the Journal of Bacteriology. He was/is a chair and a permanent member of several NIH panels
including “Computational tools for Human Microbiome Project”, “Biodata Management and
Analysis”, “Prokaryotic Cell and Molecular Biology”. His research interests are in the area of
computational genomics and protein sequence analysis with a focus on signal transduction,
protein-protein interactions, molecular modeling and dynamics, all being viewed through the
prism of Evolution.
