A Novel Locally c-di-GMP-Controlled Exopolysaccharide Synthase Required for Bacteriophage N4 Infection of Escherichia coli

Key findings in model organisms led to the concept of “local” signaling, challenging the dogma of a gradually increasing global intracellular c-di-GMP concentration driving the motile-sessile transition in bacteria. In our current model, bacteria dynamically combine both global and local signaling modes, in which specific DGCs and/or PDEs team up with effector/target systems in multiprotein complexes.

Bacteriophage N4 large terminase: expression, purification and X-ray crystallographic analysis

Genome packaging is a critical step in the assembly of dsDNA bacteriophages and is carried out by a powerful molecular motor known as the large terminase. To date, wild-type structures of only two large terminase proteins are available, and more structural information is needed to understand the genome-packaging mechanism. Towards this goal, the large and small terminase proteins from bacteriophage N4, which infects theEscherichia coliK12 strain, have been cloned, expressed and purified. The purified putative large terminase protein hydrolyzes ATP, and this is enhanced in the presence of the small terminase. The large terminase protein was crystallized using the sitting-drop vapour-diffusion method and the crystal diffracted to 2.8 Å resolution using a home X-ray source. Analysis of the X-ray diffraction data showed that the crystal belonged to space groupP212121, with unit-cell parametersa= 53.7,b= 93.6,c= 124.9 Å, α = β = γ = 90°. The crystal had a solvent content of 50.2% and contained one molecule in the asymmetric unit.

Insight into DNA and Protein Transport in Double-stranded DNA Viruses: The Structure of Bacteriophage N4

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008