PARENT SESSION
Posters P6C Photosynthesis, respiration and alternative electron sinks. Abstracts (660-680)

Global induction of glucose catabolism related-genes in Synechocystis during the early stage of photomixotrophic growth. Jee-Youn Ryu^*,1, Sanghyeob Lee², Eunjoo Chung², Ji Young Song¹, Sang-Bong Choi³, Doil Choi², Youn-Il Park¹, ¹ Department of Biology, Daejeon, Korea² Laboratory of Plant Genomics, Daejeon, Korea³

ABSTRACT- The transcriptional profiling of cyanobacterial genes associated with the central carbon and energy metabolism during transition from photoautotrophic to photomixotrophic growth condition was investigated using the DNA microarray. Upon addition of 10 mM glucose to photoautotrophically grown Synechocystis sp. PCC 6803 cells under illumination, on immediate increase in the NADPH content in conjunction with the stimulation of respiratory O₂ uptake rate and cytosolic alkalization were observed while photosynthetic activity measured as O₂ exchange rates and photochemical efficiencies of both photosystems slightly declined. In agreement with these results, transcript abundance of genes related to both production and oxidation of NADPH, i.e., the oxidative pentose phosphate pathway (OPPP), TCA cycles, respiratory electron transport and ATP synthase were highly up-regulated, while transcription of some genes involved in the photosynthesis and the RPPP were down regulated. These findings suggest that genes related to glucose catabolism are transcriptionally regulated by glucose and cytoplasmic respiratory electron transport rather than that in the thylakoid membrane is mainly responsible for the increased respiratory activity. And some glucose sensitive genes did not respond to glucose by inactivation of glucoskinase. These results suggest that at least expression of these genes is mediated by glucokinase or its downstream.

KEY WORDS: glucose, Synechocystis, carbon metabolism, DNA microarry