Identification and Characterization ofRe-Citrate Synthase in Syntrophus aciditrophicus

Abstract

Glutamate is usually synthesized from acetyl coenzyme A (acetyl-CoA) via citrate, isocitrate, and 2-oxoglutarate. Genome analysis revealed that in Syntrophus aciditrophicus, the gene for Si-citrate synthase is lacking.

Dethiosulfatarculus sandiegensis gen. nov., sp. nov., isolated from a methanogenic paraffin-degrading enrichment culture and emended description of the family Desulfarculaceae

“…The genome lacked citrate synthase. However, it contains a re-citrate synthase that catalyses the formation of citrate from acetyl-CoA and oxaloacetate (Gottschalk & Barker, 1966;Kim et al, 2013;Li et al, 2007). Interestingly, re-citrate synthase is oxygensensitive and thus can only be found in anaerobic organisms.…”

Two Pathways for Glutamate Biosynthesis in the Syntrophic Bacterium Syntrophus aciditrophicus

“…The formation of only labeled malate confirms the functioning of a Re-citrate synthase in cell extracts of S. aciditrophicus. Note that this experiment already had been described in a previous paper (8), but the referred Fig. 4 erroneously showed the result with recombinant Re-citrate synthase, rather than with the cell extract, which is depicted in Fig.…”

“…Activity was measured using succinate thiokinase (succinyl-CoA synthetase, ␣-chain SYN_00001, and ␤-chain SYN_03227) present in the cell extract to synthesize succinylCoA. Cell extracts of S. aciditrophicus were prepared anoxically as previously described (8). The 1-ml reaction mixture contained 100 mM morpholinepropanesulfonic acid (MOPS)-KOH (pH 7.5), 1 mM thiamine diphosphate, 1 mM dithioerythritol, 5 mM MgCl 2 , 1 mM methyl viologen, 1 mM ATP, 500 M CoASH, and 1 mM succinate in a septum-sealed cuvette.…”

“…At the time when the S. aciditrophicus genome was sequenced, the gene for Re-citrate synthase was not known. Subsequently, the gene for Re-citrate synthase was identified in Clostridium kluyveri (7) and shown to be present in S. aciditrophicus (8). Thus, it is likely that S. aciditrophicus synthesizes glutamate using a Re-citrate synthase and the oxidative branch of the Krebs cycle (Fig.…”

Therapeutic potential of targeting glucose metabolism in glioma stem cells

“…In cancer cells, glucose provides acetyl-CoA that condenses with oxaloacetate to produce citrate and 2-HG production [24,25]. As a critical metabolite, a-ketoglutarate (a-KG) is actively carboxylated by the NADPH-linked mitochondrial and cytosolic IDH1/2 to form citrate and 2-HG, respectively [25,26].…”