Endogenous clock-mediated regulation of intracellular oxygen dynamics is essential for diazotrophic growth of unicellular cyanobacteria.

The discovery of nitrogen fixation in unicellular cyanobacteria provided the first clues for the existence of a circadian clock in prokaryotes. However, recalcitrance to genetic manipulation barred their use as model systems for deciphering the clock function. Here, we explore the circadian clock in the now genetically amenable Cyanothece 51142, a unicellular, nitrogen-fixing cyanobacterium.

Carbon availability affects diurnally controlled processes and cell morphology of Cyanothece 51142.

Cyanobacteria are oxygenic photoautotrophs notable for their ability to utilize atmospheric CO2 as the major source of carbon. The prospect of using cyanobacteria to convert solar energy and high concentrations of CO2 efficiently into biomass and renewable energy sources has sparked substantial interest in using flue gas from coal-burning power plants as a source of inorganic carbon. However, in order to guide further advances in this area, a better understanding of the metabolic changes that occur under conditions of high CO2 is needed.

Variations in the rhythms of respiration and nitrogen fixation in members of the unicellular diazotrophic cyanobacterial genus Cyanothece.

In order to accommodate the physiologically incompatible processes of photosynthesis and nitrogen fixation within the same cell, unicellular nitrogen-fixing cyanobacteria have to maintain a dynamic metabolic profile in the light as well as the dark phase of a diel cycle. The transition from the photosynthetic to the nitrogen-fixing phase is marked by the onset of various biochemical and regulatory responses, which prime the intracellular environment for nitrogenase activity. Cellular respiration plays an important role during this transition, quenching the oxygen generated by photosynthesis and by providing energy necessary for the process.

Novel metabolic attributes of the genus cyanothece, comprising a group of unicellular nitrogen-fixing Cyanothece.

Unlabelled: The genus Cyanothece comprises unicellular cyanobacteria that are morphologically diverse and ecologically versatile. Studies over the last decade have established members of this genus to be important components of the marine ecosystem, contributing significantly to the nitrogen and carbon cycle. System-level studies of Cyanothece sp.

Diurnal rhythms result in significant changes in the cellular protein complement in the cyanobacterium Cyanothece 51142.

Cyanothece sp. ATCC 51142 is a diazotrophic cyanobacterium notable for its ability to perform oxygenic photosynthesis and dinitrogen fixation in the same single cell. Previous transcriptional analysis revealed that the existence of these incompatible cellular processes largely depends on tightly synchronized expression programs involving ∼30% of genes in the genome.

Global proteomics reveal an atypical strategy for carbon/nitrogen assimilation by a cyanobacterium under diverse environmental perturbations.

Cyanobacteria, the only prokaryotes capable of oxygenic photosynthesis, are present in diverse ecological niches and play crucial roles in global carbon and nitrogen cycles. To proliferate in nature, cyanobacteria utilize a host of stress responses to accommodate periodic changes in environmental conditions. A detailed knowledge of the composition of, as well as the dynamic changes in, the proteome is necessary to gain fundamental insights into such stress responses.

Integrative analysis of large scale expression profiles reveals core transcriptional response and coordination between multiple cellular processes in a cyanobacterium.

Background: Cyanobacteria are the only known prokaryotes capable of oxygenic photosynthesis. They play significant roles in global biogeochemical cycles and carbon sequestration, and have recently been recognized as potential vehicles for production of renewable biofuels. Synechocystis sp.

A systems-level analysis of the effects of light quality on the metabolism of a cyanobacterium.

Photosynthetic organisms experience changes in light quantity and light quality in their natural habitat. In response to changes in light quality, these organisms redistribute excitation energy and adjust photosystem stoichiometry to maximize the utilization of available light energy. However, the response of other cellular processes to changes in light quality is mostly unknown.

Effect of continuous light on diurnal rhythms in Cyanothece sp. ATCC 51142.

Background: Life on earth is strongly affected by alternating day and night cycles. Accordingly, many organisms have evolved an internal timekeeping system with a period of approximately 24 hours. Cyanobacteria are the only known prokaryotes with robust rhythms under control of a central clock.

Arabidopsis transcriptome reveals control circuits regulating redox homeostasis and the role of an AP2 transcription factor.

Sensors and regulatory circuits that maintain redox homeostasis play a central role in adjusting plant metabolism and development to changing environmental conditions. We report here control networks in Arabidopsis (Arabidopsis thaliana) that respond to photosynthetic stress. We independently subjected Arabidopsis leaves to two commonly used photosystem II inhibitors: high light (HL) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU).

The genome of Cyanothece 51142, a unicellular diazotrophic cyanobacterium important in the marine nitrogen cycle.

Unicellular cyanobacteria have recently been recognized for their contributions to nitrogen fixation in marine environments, a function previously thought to be filled mainly by filamentous cyanobacteria such as Trichodesmium. To begin a systems level analysis of the physiology of the unicellular N(2)-fixing microbes, we have sequenced to completion the genome of Cyanothece sp. ATCC 51142, the first such organism.

Integration of carbon and nitrogen metabolism with energy production is crucial to light acclimation in the cyanobacterium Synechocystis.

Light drives the production of chemical energy and reducing equivalents in photosynthetic organisms required for the assimilation of essential nutrients. This process also generates strong oxidants and reductants that can be damaging to the cellular processes, especially during absorption of excess excitation energy. Cyanobacteria, like other oxygenic photosynthetic organisms, respond to increases in the excitation energy, such as during exposure of cells to high light (HL) by the reduction of antenna size and photosystem content.