Glycogen deficiency impairs diurnal energy metabolism and cell division in Synechocystis
Hofer, J. M.; Schulze, T.; Witting, L.; Laker, B.; Krueger, S.; Westhoff, P.; Kohlheyer, D.; Weber, A. P. M.; Eisenhut, M.
Plant Signaling
Cyanobacteria are the ancestors of the chloroplasts inside every plant cell in your garden — understanding how they manage energy through day and night cycles reveals the deep evolutionary rules that still govern how your tomatoes and sunflowers power themselves.
Tiny photosynthetic bacteria called cyanobacteria store sugar during the day, much like plants do, to fuel themselves through the night. Researchers removed the gene that lets these bacteria make their stored sugar and found the bacteria became super sensitive to light during the day and energy-starved at night. When morning came, the sugar-deficient bacteria took much longer to wake up and start dividing — like a person trying to run a marathon after skipping dinner.
Key Findings
Glycogen-deficient mutants showed severe energy depletion at night, with reduced ATP levels and depleted central carbon metabolites, demonstrating glycogen is the primary nighttime fuel source.
During daytime, mutant cells compensated by downregulating photosynthesis genes to avoid dangerous energy overload — a stress response that limited their ability to grow normally.
After dawn, glycogen-deficient cells experienced extended lag phases and delayed cell divisions, showing they could not efficiently restart growth without overnight glycogen reserves.
chevron_right Technical Summary
Scientists discovered that cyanobacteria (ancient photosynthetic microbes) absolutely depend on their stored sugar (glycogen) to survive the night and restart growth at dawn. Without it, their energy systems collapse in the dark and they struggle to divide when light returns.
Abstract Preview
Diurnal changes in light availability are a defining feature of life on Earth. Photoautotrophic organisms therefore store reduced carbon during the day to sustain energy metabolism at night. In cya...
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