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Even Algae Get Stressed

Atypical stress response for algae influences photosynthetic productivity

Synechocystis 6803 grown in liquid and solid media (left) and as seen under a light microscope (right). Images courtesy of Michelle Liberton.

Blue-green algae, or cyanobacteria, are responsible for nearly half of the photosynthesis necessary for sustaining life on earth and can be used to create renewable, carbon-neutral biofuels. They’ve been studied by hundreds of laboratories over decades, yet many aspects of their physiology remain poorly understood. As part of a Grand Challenge research effort, scientists at EMSL and other laboratories have discovered how these critical bacteria use many proteins and how they respond to varying natural conditions.

Typical research on cyanobacteria often focus on pampered conditions that result in a fast, high yield, but those conditions bear little resemblance to what these bacteria face in nature. Using a systems biology approach, a team of scientists from Washington University in St. Louis; EMSL; Pacific Northwest National Laboratory (PNNL); The Hebrew University of Jerusalem; and Texas Tech University conducted a large-scale analysis of a particular, well known cyanobacterium under 33 environmental conditions. The work focused on understanding how the well-known cyanobacterium Synechocystis 6803 altered its protein components in response to various stresses.

EMSL’s extensive capability with large-scale mass spectrometers applied to proteomic analysis allowed the team to produce a high-quality dataset that covers 53 percent of the predicted proteome, the most comprehensive functional and quantitative analysis for any photosynthetic organism to date. The scientists discovered that, regardless of the type of stress or duration, the cyanobacterium immediately activates alternate pathways to acquire carbon and nitrogen. Analysis of these dynamic changes in the proteome provides insights into cellular adaptations to environmental perturbations.  

This work was conducted as part of EMSL’s Membrane Biology Grand Challenge. Researchers are using a systems approach to understand the network of genes and proteins that govern the structure and function of membranes and their components responsible for photosynthesis and nitrogen fixation in blue-green algae. The goal of the Grand Challenge is to be able to engineer oxygenic microbes with enhanced carbon sequestration abilities.

Scientific Impact: By using this type of large-scale proteomics approach, scientists can gain new insights into how these important bacteria function in nature. The results show that a key cellular adaptation leads to the activation of alternate pathways for the acquisition of carbon and nitrogen, which are the two major sinks for reducing powers generated by the photosynthetic light reactions in cyanobacteria.

Societal Impact:  Understanding the functioning of cyanobacteria will allow engineers to use them more effectively in the generation of carbon-neutral biofuels.

Reference:  Wegener, K.M., A.K. Singh, J.M. Jacobs, T. Elvitigala, E.A. Welsh, N. Keren, M.A. Gritsenko, B.K. Ghosh, D.G. Camp II, R.D. Smith, and H.B. Pakrasi. “Global Proteomics Reveal an Atypical Strategy for Carbon/Nitrogen Assimilation by a Cyanobacterium Under Diverse Environmental Perturbations.”  Molecular and Cellular Proteomics, published online September 21, 2010. DOI: 10.1074/mcp.M110.000109

Acknowledgement:  This work was supported as part of the Membrane Biology Scientific Grand Challenge project at EMSL, a DOE/BER national scientific user facility located on the campus of Pacific Northwest National Laboratory (PNNL) in Richland, Washington. Additional support was from the National Science Foundation grants FIBR EF0425749 and MCB 0745611.

Released: January 03, 2011