Seminar series on The Evolution of Genomic Architecture - Tal Dagan: Being a plasmid - consideration of copy number, DNA topology and segregation in plasmid genome evolution
- Date: Sep 3, 2019
- Time: 11:00 AM - 12:00 PM (Local Time Germany)
- Speaker: Tal Dagan from CAU Kiel, Germany
- Here you find more information on the speaker: http://www.mikrobio.uni-kiel.de/de/ag-dagan
- Location: MPI Plön
- Room: Lecture hall
- Host: Jenna Gallie & Julien Dutheil
Abstract:
Plasmids are genetic elements that
colonize and replicate in prokaryotic cells. Plasmids play a major role in
prokaryote ecology and evolution, as they are ubiquitous in all phyla and
across all habitats. Plasmids are distinct from chromosomes in several
properties, including a relatively small genome size, their ploidy level that
can be dynamic, their frequency in the population that can be spatially and
temporally heterogeneous, and their mobility. These properties correspond to
known determinants of molecular evolution such as mutational supply,
segregational drift, population size, and lateral transfer. We studied the
fundamental principles that govern plasmid genome evolution using experimental evolution
of model plasmids as well as simulated evolution. Our results reveal that
segregational drift of multicopy plasmids interferes with the retention and
fixation of novel plasmid variants. Depending on the selection pressure on
newly emerging variants, plasmid genomes may evolve slower than haploid
chromosomes, regardless of their higher mutational supply. Our results further
reveal dependency of plasmid stability evolution on the coordination of plasmid
transcription and replication, which is challenging in small genomes. Our
studies thus reveal plasmid properties that are important for the evolution of
successful autonomously replicating genetic elements.
PS:
for the phylogenetics enthusiasts – I will include a short report at the end on
our current developments on the inference of ancestor-descendant relations in
phylogenomics.