Diurnal metabolic control in cyanobacteria requires perception of second messenger signaling molecule c-di-AMP by the carbon control protein SbtB

Abstract

The carbon sensor SbtB perceives diurnal oscillation of c-di-AMP to control glycogen synthesis and nighttime survival.

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

“…3), may be involved in chloride transport (Kobayashi et al ., 2006). These expression changes are therefore consistent with the recently reported low osmotic stress tolerance of Δ dacA (Selim et al ., 2021).…”

“…The generation of the DsbtB (Dslr1513) and DdacA (Dsll0505) mutants has been previously described (Selim et al, 2018(Selim et al, , 2021. The Dcya1 (Dslr1991) knockout mutant was generated by deletion of slr1991.…”

“…Like other PII proteins, SbtB can bind different effector molecules, which modulate its flexible T‐loop, a structure that is important for mediating interactions with potential binding partners. However, unlike PII, SbtB binds not only to ATP, ADP, or AMP, but also to the second messengers cAMP (Selim et al ., 2018) and c‐di‐AMP (Selim et al ., 2021). The second messenger cAMP has previously been proposed to act as a C i ‐sensing signal, since the activity of the cAMP‐producing soluble adenylate cyclase is modulated by different C i concentrations (Cann et al ., 2003; Hammer et al ., 2006).…”

“…The other second messenger, c‐di‐AMP, has been previously linked to potassium homeostasis and osmoregulation (Agostoni et al ., 2018; Stülke & Krüger, 2020). In cyanobacteria, c‐di‐AMP is also involved in growth regulation under light : dark conditions (Rubin et al ., 2018), as it controls glycogen metabolism during diurnal cycles via SbtB (Selim et al ., 2021).…”

Sustained Control of Pyruvate Carboxylase by the Essential Second Messenger Cyclic di-AMP in Bacillus subtilis

“…Of the three scenarios, interaction of the apo c-di-AMP receptors with their targets might be preferred, since the evolution of protein interaction surfaces may have fewer constraints than the evolution of second-messenger binding pockets that require binding under standard conditions (potassium sufficiency). Strikingly, in cyanobacteria, the c-di-AMP receptor protein SbtB binds and activates its target, GlgB, an enzyme required for glycogen synthesis in the c-di-AMP-bound state ( 41 ). It will be interesting to see whether future research will discover DarB targets that interact with the c-di-AMP-bound form of DarB and whether, for the other c-di-AMP binding signal transduction proteins, the interactions also occur with the apo-proteins.…”