GBB Seminar Series – Invited Speaker

Prof. Victor de Lorenzo CSIC, Madrid, Spain

The secret life of Pseudomonas putida

Visualization of a chemical factory typically involves a suite of modules, pipes, valves, flows, chimneys etc. that are located in time and space following a given relational logic. In contrast, bacterial cells are often imagined as one-pot reactors where a large number of reactions happen at the same time and the same place. Although bacterial cytoplasm is not compartimentalized this does not mean that cellular components are randomly organized or free to diffuse. Many studies have shown that proteins –by themselves and forming part of complexes are located at particular regions of bacterial cells. We have investigated the subcellular localization of the molecular machineries that run the whole gene expression flow of Pseudomonas putida during catabolism of m-xylene. Fluorescent protein fusions to subunits of RNA polymerase (RNAP) and ribosomes, microscopy and image analysis showed that RNAP co-localized in 3D with chromosomal DNA, while ribosomal proteins were abundant only outside of nucleoid. FISH experiment revealed that xyl transcripts were accumulated at specific cell addresses rather than diffused throughout. DNA-RNA FISH indicated such xyl transcripts to be adjacent to these template DNA. However, RNA molecules stemming from the TOL plasmid were constrained in DNA-free subcellular regions, where ribosomal proteins are enriched. In contrast, catabolic enzymes showed a remarkable mobility in the cytoplasm, as revealed by single-molecule tracking. It is thus possible that the macromolecules involved in the flow of genetic information from the TOL plasmid have a fixed 3D dynamics in P. putida in order to optimize the performance of the whole catabolic process.

Thursday, May 21 / 4.15pm / room 5159.0029, Energy Academy