E 2 - Peter Graumann

Cross talk between a conjugative plasmid and its Bacillus subtilis host cell during stress adaptation








Prof. Dr. Peter Graumann

LOEWE Center for Synthetic Microbiology (SYNMIKRO) 

Hans-Meerwein-Straße, 35043 Marburg

+49 - 6421 - 2822210




Research summary:

Conjugative plasmid pLS20 affects many cellular processes of its host, including differentiation into specialized subpopulations of cells, and confers considerable stress resistance during active conjugation. During the limited time window of active conjugation, about 5% of all host genes are up- or downregulated, showing that extrachromosomal elements can strongly interfere with the global transcription profile of the host chromosome. Conversely, the host cell affects the timing of conjugation, which is centrally regulated by a plasmid-encoded repressor that is controlled by a quorum-sensing Rap/Phr system. We will analyse how the cross talk between plasmid and chromosome occurs on a molecular genetic and biochemical level. We have preliminary evidence that conjugation activity is affected through host sigma factors that respond to envelope stress. It will be of interest to elucidate how the plasmid/host systems adapt to different stress conditions, and how pLS20 affects stress resistance of  B. subtilis. Like other conjugative plasmids, pLS20 affects the development of multicellularity also known as biofilm formation.

However, it is yet unclear how plasmids can spread through biofilms, given that plasmids interfere with the differentiation of cells into specialized subpopulations and that the state of the host cell influences DNA transfer of the plasmid. Therefore, we will visualize plasmid mobility in growing biofilms, and investigate if this process is affected through different stress conditions and/or depends on specific cell types. Our work will shed light on the co-adaptation of mobile DNA elements and their host cells to changes in the environment.