Nina Kamennaya | Accumulation of phosphate in periplasm of marine cyanobacteria

Nina Kamennaya - Ben-Gurion University of the Negev, Israel
Homepage: in.bgu.ac.il/e...
Accumulation of phosphate in periplasm of marine cyanobacteria
Gram-negative bacteria acquire phosphate (Pi) by maintaining its periplasmic concentration below the environmental levels. We recently described an extracellular Pi buffer, which appears to counteract the gradient required for Pi diffusion. In my presentation, I will present the most recent study that explores the mechanism of extracellular Pi buffer accumulation in marine cyanobacteria. I will demonstrate that various treatments to outer membrane (OM) constituents do not affect the buffered Pi because the marine cyanobacteria accumulate Pi in their periplasm. The periplasmic Pi that can be removed hypo-osmotically is gradually imported into the cytoplasm through ATP-powered transport. Though the proton motive force (PMF) is not required to keep Pi in the periplasm, the accumulation of Pi into the periplasm across the OM is PMF-dependent. Furthermore, it can be enhanced by light energy, but it does not involve the ATP-powered transport. Because the conventional mechanism of Pi-specific transport cannot explain Pi accumulation in the periplasm, we propose a new model of Pi accumulation in marine cyanobacteria, where periplasmic Pi anions pair with chemiosmotic cations of the PMF.
This talk is part of the CyanoWorld online seminar series, hosted by Nicolas Schmelling and Ilka Axmann, and was held on Zoom on January 27th, 2022.
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