AtpΘ is an inhibitor of F0F1 ATP synthase to arrest ATP hydrolysis during low-energy conditions in cyanobacteria

Expression of the Cyanobacterial F o F 1 ATP Synthase Regulator AtpΘ Depends on Small DNA-Binding Proteins and Differential mRNA Stability

“…The atpT mRNA level was low but detectable at a light intensity of 40 μmol photons m −2 s −1 but much higher in the dark, and the addition of 10 mM glucose neutralized the increased mRNA accumulation in darkness ( Fig. 2A and B ), consistent with previous results ( 17 ). This fact excludes the possibility that the dark induction of atpT expression was controlled by a photoreceptor.…”

“…Instead, cyanobacteria encode a small amphipathic protein, AtpΘ, which was shown to prevent the ATPase activity of ATP synthase ( 17 ). AtpΘ is encoded by the atpT gene, and likely homologs of atpT were detected in all available cyanobacterial genomes.…”

“…In the model cyanobacterium Synechocystis sp. PCC 6803 ( Synechocystis 6803), AtpΘ accumulates during conditions that potentially weaken the proton gradient, such as darkness ( 17 , 18 ). The addition of glucose neutralized the strong dark-induced atpT transcript accumulation, while the further addition of a chemical uncoupler or an electron transport inhibitor restored the high transcript accumulation in the dark ( 17 ).…”

“…PCC 6803 ( Synechocystis 6803), AtpΘ accumulates during conditions that potentially weaken the proton gradient, such as darkness ( 17 , 18 ). The addition of glucose neutralized the strong dark-induced atpT transcript accumulation, while the further addition of a chemical uncoupler or an electron transport inhibitor restored the high transcript accumulation in the dark ( 17 ). These findings suggested that the regulation of atpT is complex and to be somehow connected to the status of the electron transport chain or proton gradient.…”

The impact of the cyanobacterial carbon‐regulator protein SbtB and of the second messengers cAMP and c‐di‐AMP on CO2‐dependent gene expression

“…Some other protein‐coding genes associated with carbon metabolism, such as the glucose transporter GlcP, malate dehydrogenase, and fructose‐bisphosphate aldolase, were also more highly expressed in HC‐grown Δ sbtB cells (Table 1). Furthermore, the ATP synthase operon sll1321‐1327 was higher expressed (Table S1), consistent with an upregulated atpT gene, encoding AtpΘ, the inhibitor of ATP hydrolysis (back reaction) of the ATP synthase complex (Song et al ., 2022). The higher ATP synthase expression correlated with a significantly higher ATP accumulation in Δ sbtB (504.9 ± 8.7 nmol ml −1 OD 750 −1 ) compared to WT (350.6 ± 36.7 nmol ml −1 OD 750 −1 ), under HC conditions.…”