Project description:In Myxococcus xanthus 55% of the more than 250 two-component signal transduction systems (TCS) genes are orphan. We hypothesized that the histidine kinase SgmT and the response regulator DigR, which comprises a DNA binding domain of the HTH_Xer type, function together to regulate gene expression. We performed genome-wide expression profiling experiments to determine wether the same set of genes are differentially expressed in the ΔdigR and ΔsgmT mutants.
Project description:In Myxococcus xanthus 55% of the more than 250 two-component signal transduction systems (TCS) genes are orphan. We hypothesized that the histidine kinase SgmT and the response regulator DigR, which comprises a DNA binding domain of the HTH_Xer type, function together to regulate gene expression. We performed genome-wide expression profiling experiments to determine wether the same set of genes are differentially expressed in the ΔdigR and ΔsgmT mutants. 3 biological replicates each; normalized ratios to vegetative cells of DK1622 (wt) Cy5
Project description:In Myxococcus xanthus, two component systems have crucial roles in regulating motility behavior and development. Here, we describe an orphan response regulator consisting of an N-terminal receiver domain and a C-terminal DNA binding domain, which is required for A- and type IV pili dependent gliding motility. Genetic evidence suggests that phosphorylation of the conserved, phosphorylatable aspartate residue in the receiver domain is required for DigR activity. Consistent with the defect in type IV pili dependent motility, a digR mutant is slightly reduced in type IV pili biosynthesis and the composition of the extracellular matrix fibrils is abnormal with an increased content of polysaccharides and decreased accumulation of the FibA metalloprotease. Using genome-wide transcriptional profiling, 118 genes were identified that are directly or indirectly regulated by DigR. These genes only include two genes, agmQ and cheY4, previously implicated in A- and type IV pili dependent motility, respectively. In silico analyses showed that 36% of the differentially expressed genes are likely to encode exported proteins. Moreover, four genes encoding homologs of ECF sigma factors, which typically control aspects of cell envelope homeostasis, are differentially expressed in a digR mutant. We suggest that the DigR response regulator has an important function in cell envelope homeostasis and that the motility defects in a digR mutant are instigated by the abnormal cell envelope and abnormal expression of agmQ and cheY4. Keywords: vegetative analysis (delta)DigR / DK1622 (wt)
Project description:In response to starvation Myxococcus xanthus initiates a developmental program that culminates in the formation of fruiting bodies inside which the rod-shaped cells differentiate to spores. Fruiting body formation depends on intercellular communication and two intercellular signals are known, the A-signal and the C-signal. Five genes have been identified which are required for A-signal synthesis. To begin to understand the function of the genes required for A-signal synthesis, we have analysed gene expression in the asgA and the asgB mutant. Keywords: Vegetative cells of WT (DK1622) and AsgA mutant (DK5057) and AsgB mutant (DK4398)
Project description:Our ChipSeq analysis show that while FrzCD does not bind DNA specific regions, ParB binds parS consistent with what as been previously shown. The FrzCD chemoreceptor from the gliding bacterium Myxococcus xanthus forms cytoplasmic clusters that occupy a large central region of the cell body also occupied by the nucleoid. FrzCD directly binds to the nucleoid and the FrzCD binding to the DNA leads to the formation of chemosensory complexes. This supra-molecular organization is required for cooperative interactions between clustered receptors, in turn important for the modulation of bacterial social behaviors.
