TY - JOUR T1 - Biochemical elucidation of citrate accumulation in Synechocystis sp. PCC 6803 via kinetic analysis of aconitase. AU - Nishii,Maki, AU - Ito,Shoki, AU - Katayama,Noriaki, AU - Osanai,Takashi, Y1 - 2021/08/24/ PY - 2021/03/11/received PY - 2021/08/04/accepted PY - 2021/8/25/entrez PY - 2021/8/26/pubmed PY - 2021/11/3/medline SP - 17131 EP - 17131 JF - Scientific reports JO - Sci Rep VL - 11 IS - 1 N2 - A unicellular cyanobacterium Synechocystis sp. PCC 6803 possesses a unique tricarboxylic acid (TCA) cycle, wherein the intracellular citrate levels are approximately 1.5-10 times higher than the levels of other TCA cycle metabolite. Aconitase catalyses the reversible isomerisation of citrate and isocitrate. Herein, we biochemically analysed Synechocystis sp. PCC 6803 aconitase (SyAcnB), using citrate and isocitrate as the substrates. We observed that the activity of SyAcnB for citrate was highest at pH 7.7 and 45 °C and for isocitrate at pH 8.0 and 53 °C. The Km value of SyAcnB for citrate was higher than that for isocitrate under the same conditions. The Km value of SyAcnB for isocitrate was 3.6-fold higher than the reported Km values of isocitrate dehydrogenase for isocitrate. Therefore, we suggest that citrate accumulation depends on the enzyme kinetics of SyAcnB, and 2-oxoglutarate production depends on the chemical equilibrium in this cyanobacterium. SN - 2045-2322 UR - https://www.unboundmedicine.com/medline/citation/34429477/Biochemical_elucidation_of_citrate_accumulation_in_Synechocystis_sp__PCC_6803_via_kinetic_analysis_of_aconitase_ DB - PRIME DP - Unbound Medicine ER -