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Poster Presentations
Day 4, June 25（Wed.）
Room P (Maesato East, Foyer, Ocean Wing)
- 4P-PM-32
Targeted Metabolomics Reveals the Essential Role of Nicotinamide Mononucleotide Adenylyltransferase (NMNAT) in Nicotinamide Adenine Dinucleotide (NAD+) Homeostasis in the Cyanobacterium Synechococcus elongatus
(1HKBU/Chem, 2HKBU/Bio, 3EIT)
oFeng Zhang1, Hai Lei Zhang2, Peng Xi Wang2, Yiji Xia2, Zong Wei Cai1,3
Cyanobacteria, a prominent model organism, are extensively used in bioenergy development, the production of bioactive compounds, and fundamental research on photosynthetic systems. Nicotinamide adenine dinucleotide (NAD), a crucial coenzyme, plays a key role in various metabolic processes within cyanobacteria. Understanding NAD metabolism and its regulatory mechanisms provides a foundational framework for numerous studies. This research demonstrates that NAD levels in cyanobacteria fluctuate rhythmically in response to light-dark cycles during cultivation. Moreover, NMN adenylyltransferase (NMNAT), an enzyme involved in the NAD salvage pathway and identified in higher animals, exhibits similar rhythmic fluctuations. Through a combination of gene editing and targeted metabolomics, we show that the NMNAT gene is likely essential for maintaining NAD homeostasis. Under dark conditions, NMNAT knockout accelerates the decline of NAD levels and enhances the response to dark-induced stress. In contrast, under light conditions, NMNAT overexpression increases NAD levels; however, prolonged overexpression inhibits cyanobacterial growth. These findings suggest that NMNAT should be precisely regulated to sustain NAD homeostasis in Cyanobacterium S. elongatus.