Phosphorylation of Phospho enol pyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO 2 Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi

Sep 10, 2017The Plant cell

Phosphorylation of a Key Enzyme Is Needed for Maximum Nighttime CO2 Fixation and Proper Circadian Clock Function in the CAM Plant Kalanchoë fedtschenkoi

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗OA ↗

Abstract

Plants with reduced dark phosphorylation of phosphopyruvate carboxylase (PPC) exhibited up to a 66% reduction in total dark period CO2 fixation.

Phosphopyruvate carboxylase kinase (PPCK) regulates PPC by phosphorylating it during the dark period.
Reduced levels of PPCK led to decreased sensitivity of PPC to feedback inhibition by malate.
Lower dark phosphorylation of PPC is associated with reduced malate accumulation at dawn.
A decrease in nocturnal starch turnover was observed alongside the reduced PPC phosphorylation.
Loss of transcript oscillations for PPCK correlated with disruptions in core circadian clock gene expression.

AI simplified

Phosphopyruvate carboxylase (PPC; EC 4.1.1.31) catalyzes primary nocturnal COfixation in Crassulacean acid metabolism (CAM) species. CAM PPC is regulated posttranslationally by a circadian clock-controlled protein kinase called phosphopyruvate carboxylase kinase (PPCK). PPCK phosphorylates PPC during the dark period, reducing its sensitivity to feedback inhibition by malate and thus enhancing nocturnal COfixation to stored malate. Here, we report the generation and characterization of transgenic RNAi lines of the obligate CAM specieswith reduced levels oftranscripts. Plants with reduced or no detectable dark phosphorylation of PPC displayed up to a 66% reduction in total dark period COfixation. These perturbations paralleled reduced malate accumulation at dawn and decreased nocturnal starch turnover. Loss of oscillations in the transcript abundance ofwas accompanied by a loss of oscillations in the transcript abundance of many core circadian clock genes, suggesting that perturbing the only known link between CAM and the circadian clock feeds back to perturb the central circadian clock itself. This work shows that clock control ofprolongs the activity of PPC throughout the dark period in, optimizing CAM-associated dark COfixation, malate accumulation, CAM productivity, and core circadian clock robustness. enol enol Kalanchoë fedtschenkoi KfPPCK1KfPPCK1KfPPCK1K. fedtschenkoi2 2 2 2

Full Text

Full text is available at the source.

View full text ↗

Phosphorylation of Phospho enol pyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO 2 Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief