SnRK1 activation, signaling, and networking for energy homeostasis

Abstract

The SnRK1 kinases are key regulators of the plant energy balance, but how their activity is regulated by metabolic status is still unclear. While the heterotrimeric kinase complex is well conserved between plants, fungi and animals, plants appear to have modified its regulation to better fit their unique physiology and lifestyle. The SnRK1 kinases control metabolism, growth and development, and stress tolerance by direct phosphorylation of metabolic enzymes and regulatory proteins and by extensive transcriptional regulation. Diverse types of transcription factors have already been implicated, with a well-studied role for the heterodimerizing group C and group S1 bZIPs. SnRK1 is also part of a more elaborate metabolic and stress signaling network, which includes the TOR kinase and the ABAsignaling SnRK2 kinases.

An abscisic acid-responsive protein interaction network for sucrose non-fermenting related kinase1 in abiotic stress response

“…This is in agreement with previous high-throughput verifications rates using an independent assay 5,48 and confirms that our curated Y2H interactions are of high quality. Additionally, these interactions occur in the nucleus, consistent with recent studies which have shown that SnRK1 relocates to the nucleus in response to stress 13,49 .…”

“…SnRK1 complexes in vivo have been shown to include the α, β and βγ regulatory subunits, with the β subunits giving substrate specificity to the SnRK1 complex 13,20,22,32 . Of the 125 SnIPs identified, 48 were deemed core SnRK1 complex interactors (core SnIPs), as they partnered with at least one of the α catalytic subunits and one of the β/βγ regulatory subunits, increasing the confidence that these 184 SnRK1-SnIP HCI may be biologically relevant (Supplementary Data 4 and Fig.…”

“…The SnRK1 heterotrimeric kinase complex comprises the α catalytic subunits (SnRK1α1/AKIN10 and SnRK1α2/AKIN11), involved in substrate phosphorylation, and three regulatory β (SnRK1β1-β3) and γ (SnRK1βγ) subunits, with complex scaffolding and subcellular localization functions 7,11,13 . In response to low energy, SnRK1 is activated by the SnRK1 activating kinase1 and 2 (SnAK1/2)/geminivirus REP interacting kinase1 and 2 (GRIK1/2), which phosphorylate SnRK1α on the conserved Tloop, similarly to the yeast and mammalian counterparts 7 .…”

Metabolite Control of Translation by Conserved Peptide uORFs: The Ribosome as a Metabolite Multisensor

“…Presumed ligands of the other CPuORFs in the network are unknown. metabolic enzymes during adaptation to a low-energy state (Crepin and Rolland, 2019). TOR responds to nutrient abundance by promoting ribosome biogenesis, cell cycle progression, and growth (Shi et al, 2018).…”

“…The signaling molecule trehalose-6-phosphate (T6P) inhibits SnRK1 activity (Crepin and Rolland, 2019). T6P is synthesized by T6P synthase from UDP-Glc and Glc-6-P and is metabolized by TPP to trehalose.…”