Project description:We installed and optimized a genetic tool that allows control over protein stability in a model cyanobacterium. This tool has potential uses for the fundamental study of cyanobacterial genes, and may be useful for the design of more sophisticated, bioindustrial cyanobacterial strains.
Project description:The catalytic core of the RNA polymerase of most eubacteria is composed of two α subunits and β, β’ and ω subunits. In Escherichia coli, the ω subunit (encoded by the rpoZ gene) has been suggested to assist β’ during RNA polymerase core assembly. The function of the ω subunit is particularly interesting in cyanobacteria because the cyanobacterial β’ is split to N-terminal γ and C-terminal β’ subunits. The ∆rpoZ strain of the cyanobacterium Synechocystis sp. PCC 6803 grew well in standard conditions although the mutant cells showed low light-saturated photosynthetic activity, low Rubisco content and accumulated high quantities of protective carotenoids and α-tocopherol. The ∆rpoZ strain contained 15% less of the primary σ factor, SigA, than the control strain, and recruitment of SigA to the RNA polymerase core was inefficient in ∆rpoZ. Thus, a cyanobacterial RNA polymerase holoenzyme lacking the ω subunit contains less frequently the primary σ factor. A DNA microarray analysis revealed that this leads to specific down-regulation of highly expressed genes, like genes encoding subunits for Rubisco, ATP synthase, NADH-dehydrogenase and carbon concentrating mechanisms. On the contrary, many genes showing only low or moderate expression in the control strain were up-regulated in ∆rpoZ. A conserved -10 region was detected in promoters showing up or down-regulation in ∆rpoZ, but -35 regions of down-regulated genes completely differed from -35 regions of up-regulated genes.
Project description:Comparative proteomics on two cyanobacterial strains with the expression of either a wild-type D1 gene (OE5) or a mutated D1 gene (OE9) in Synechococcus elongatus PCC 7942.
