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Fig. 7 | BMC Evolutionary Biology

Fig. 7

From: Minimal tool set for a prokaryotic circadian clock

Fig. 7

Schematic overview of the circadian clock in Synechococcus 7942. Shown is the protein network in which the clock proteins are integrated based on [20, 3653, 103, 139, 152]. The plastoquinone pool and ATP/ADP ratio serve as input signals to entrain the circadian clock with the environment and metabolic state of the cell. The signals are recognized by the input factors LdpA and CikA and the core clock factors KaiA and KaiC. Other input factors are Pex, and the CikA interaction partner NhtA, PrkE, IrcA, and CdpA. The stimulating effect of KaiA on KaiC is antagonized by KaiB. The output of the clock is comprised by SasA, CikA, RpaA, RpaB, LabA, LalA, Crm, and CpmA. SasA interacts with KaiC and further phosphorylates RpaA, whereas CikA acts as a phosphatase on RpaA. RpaA together with RpaB controls global gene expression as well as the expression of the kaiBC cluster. Solid lines represent established biochemical interactions whereas dashed lines represent inferred interactions. The seven most interconnected factors we found in our co-occurrence analysis are highlighted in green. Factors colored in light grey showed no co-occurrence in the Fisher’s exact test and are present in < 90% of all observed systems. Asterisks (*) indicate the factors missing in Prochlorococcus

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