Microbiology Monthly Newsletter for Microbiology at the Department of Cell & Molecular Biology Lundberg Laboratory, Göteborg University [ January 1999 ] [ February 1999 ] [ March 1999 ] [ April 1999 ] [ May 1999 ] [ June 1999 ] [ July-August 1999 ] [ September 1999 ] [ October 1999 ] March 1999 Scientific Contributions Our first publications for 1999 in reprint forms are starting to come in. Stefan Hohmann, Lena Gustafsson and collaborators shed some new light on the mechanisms of osmoregulation in yeast cells. They demonstrate that yeast cells regulate glycerol accumulation partly by a channel protein called Fps1p. This channel protein, which belongs to the MIP family, is localized in the plasma membrane and is involved in glycerol export. The paper demonstrates, by using different Fps1p mutants, that this channel is important in promoting glycerol export during hypo-osmotic shock as well as reducing glycerol export rates during hyperosmotic stress. During prolonged periods of hyperosmotic stress the cell can compensate for the latter phenotype by overproducing glycerol. Nevertheless, the Fps1p protein is clearly an important player in yeast osmoadaptation. In a minireview, V. Norris, T. Nyström, and colleagues discuss the possibility of using drugs targeted against phosphorylation of signal transduction pathways in antibacterial therapies. This is called the "Jekyll and Hyde approach". The arguments are based on the fact that some proteins involved in signal transduction are only phosphorylated in pathogenic E. coli strains. Notably the TypA tyrosine phosphoprotein involved in virulence and rearrangements in the host cell cytoskeleton that leads to actin-rich pedestals are present in both avirulent and virulent strains but only phosphorylated in virulent ones. In addition, phosphorylation of TypA is apparently required for its function in virulence. In view of the fact that phosphorylation of some specific proteins can be inhibited and reversed by some drugs (notably, kirromycin inhibits threonine phosphorylation of elongation factor Tu) it is proposed that a therapy based on the manipulation of phosphorylation could, in principle, be devised to alter virulence and to convert Mr Hyde back to Dr Jekyll. Guest and Extra Seminar Tom Silhavy, Princeton University, is visiting us on the 14th of April. He will give a seminar at 13.00 in Åke Göransson on "Genetic analysis of protein secretion in E. coli". This is NOT the same seminar as he will give at the annual meeting for the Swedish society of Microbiology in Lund. For those that are not familiar with Tom Silhavy’s work, he is one of the grandmasters of bacterial genetics and has been working on topics such as osmoregulation, signal transduction and protein secretion. He is also the author of several well-known books, such as "Experiments with Gene Fusions", "The Power of Bacterial Genetics" and "Two Component Signal Transduction". The seminar will be high-class so check it out! His homepage address is: http://www.molbio.princeton.edu/silhavy/silhavy.html New Faces Miki Jishage is a new post doc working in T. Nyström’s lab. She was a graduate student with Prof. Akira Ishihama in Japan and has isolated a new protein that binds sigma70, the houskeeping sigma factor in E. coli. This factor, Rsd, appears to down-regulate expression of some, but not all, genes requiring sigma70 for expression. She will be working with Anne Farewell on mechanisms of global gene regulation in E. coli. Hugo Aguilaniu from France is a graduate student visiting Lena Gustafsson and Christer Larsson. He is elucidating whether there is a possible coupling between respiratory activity and oxidation of targets proteins in growing and starving yeast cells. Scientific Meetings Interfacial processes from the molecular to the global scale, September 26-30, Deerhurst Resort, Huntsville, Ontario, Canada. 1999 International symposium on subsurface microbiology, August 22-27, Vail, Colorado, USA. Cellular responses to oxidative and osmotic stress: Sensing, signalling and gene expression. August 28 - September 1, Egmond aan Zee, the Netherlands. Happy Easter, Thomas