Transcriptomic analysis of cyanobacterial alkane production
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ABSTRACT: To identify transcriptional adaptations associated with increased alkane production in Nostoc punctiforme, we performed comparative transcriptomic analysis of an alkane overproduction strain. RNA-seq data identified a large number of highly up-regulated genes in the overproduction strain potentially involved in rRNA processing, mycosporine-glycine production, and synthesis of non-ribosomal peptides including nostopeptolide A. Other up-regulated genes encoding helical carotenoid proteins, stress-induced proteins, and those for microviridin synthesis were also up-regulated. The presence of several up-regulated genes or operons on multi-copy plasmids resulted in reduced alkane production, indicating possible targets for mutagenesis that might limit lipid droplet and alkane production.
Project description:Change in gene expression for a wild-type (Nostoc punctiforme ATCC 29133) and hmpD-deletion strain (UCD 543) of Nostoc punctiforme ATCC 29133 over the time course of hormogonium development This study is further descirbed in Risser, D.D. and Meeks, J.C. 2013. Comparative transcriptomics with a motility deficient mutant leads to identification of a novel polysaccharide secretion system in Nostoc punctiforme. Molecular Microbiology
Project description:Change in gene expression for a wild-type (Nostoc punctiforme ATCC 29133) and hmpD-deletion strain (UCD 543) of Nostoc punctiforme ATCC 29133 over the time course of hormogonium development This study is further descirbed in Risser, D.D. and Meeks, J.C. 2013. Comparative transcriptomics with a motility deficient mutant leads to identification of a novel polysaccharide secretion system in Nostoc punctiforme. Molecular Microbiology Total RNA from 3 biological replicates at each time point from 0 to 24 hours after hormogonium induction was converted to cDNA, dye-labled and hybridized to nimblegen 12x135k array slides
Project description:Change in gene expression for wild-type Nostoc punctiforme ATCC 29133, or three derivative strains with sigma factors deleted, over the time course of hormogonium development
Project description:Nostoc punctiforme is a filamentous cyanobacterium capable if differentiating normal vegetative cells into nitrogen fixing heterocysts and spore-like akinetes. Here the effects of a sigma factor (sigG) mutation on the transcriptome was analyzed under 1) normal vegetative growth, and 2) following akinete induction. A zwf strain grown with fructose differentiates into akinetes following transfer to darkness. A DNA microarray was used to compare gene expression from the zwf strain to a zwf sigG double mutant two days following akinte induction by darkness.
Project description:Nostoc cyanobacteria are capable to form symbiotic relationships with plants, transitioning to a heterotrophic lifestyle in return for providing bioavailable nitrogen to the host. The diazotrophic photoautotrophs also serve as a hub for a specialized heterotrophic bacterial community whose physiological contributions are poorly understood. By comparing the axenic strain N. punctiforme PCC 73102 and the related strains Nostoc sp. KVJ2 and KVJ3, which still maintain their heterotrophic microbiome, we were able to demonstrate an almost obligate dependence of the cyanobacteria on the heterotrophic partners under carbon-limiting conditions. Detailed analysis of the intimate bilateral relationship between Nostoc punctiforme and the isolate Agrobacterium tumefaciens Het4 using multi-omics technologies and microscopy uncovered a complex partnership characterized, among other traits, by competition for iron and facilitation for carbon. Although competitive interactions with A. tumefaciens Het4 compromise nitrogen fixation and stimulate the degradation of cyanophycin, mutualistic dependency prevails under inorganic carbon limitation. Both the absence of the high affinity bicarbonate uptake transporter SbtA and the prevalent extracarboxysomal localization of the carbon-fixing enzyme RubisCO as detected by immunofluorescence microscopy suggest a weak carbon concentrating mechanism in N. punctiforme that enforces a dependence on heterotrophic bacteria. Further, immunofluorescence, electron microscopic and proteomic analyses reveal a pronounced extracellular recycling of proteins under N- and C-limiting conditions. The pivotal influence of heterotrophic bacteria on symbiotic Nostoc strains should be considered when analyzing these strains, especially in the free-living state, and also sheds new light on the benefit to Nostoc of the provision of organic carbon by plant hosts.