Project description:To identify the mechanisms of the adaptation to terrestrial ecosystems, an RNA-seq based transcriptome analysis was conducted on a desiccation resistant cyanobacterium, Nostoc sp. MG11.
Project description:To investigate the function of All0854, we constructed the all0854 deletion mutant Mall0854, in which all0854 was knocked out by CRISPER-cpf1. We then performed gene expression profiling analysis using data obtained from RNA-seq of wide type Nostoc sp. PCC 7120 and Mall0854.
Project description:Proteogenomics analysis was employed to refine the genome annotation and provide new insights into nitrogen metabolism of Nostoc sp. PCC 7120.
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.
