SCyCode The Autotrophy-Heterotrophy Switch in Cyanobacteria: Coherent Decision-Making at Multiple Regulatory Layers

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Cyanobacterial PFKs were thought to be ATP dependent, but isolation and characterisation of 2 PFK isoenzymes from Synechocystis revealed that they belong to the PFK-A family, use ADP as phosphate donor and form a separate phylogenetic class. Their allosteric regulation via 3-PG and ATP respectively allow for flexible switching between aactive and inactive enzymes dependent on the light and carbon status.

Glucose-6-phosphate dehydrogenase (G6PDH), the enzyme that catalyzes the first step of the oxidative pentose phosphate (OPP) pathway, plays a key role in this process. G6PDH is produced at the onset of nitrogen starvation but remains inactive in dormant cells, only to be rapidly reactivated when nitrogen is restored. In this study, we investigated the mechanisms underlying this enzymatic regulation and found that G6PDH inactivation is primarily due to the accumulation of inhibitory metabolites. ...

Abstract The enzyme Glucose-1-phosphate adenylyltransferase (GlgC, EC:2.7.7.27) catalyses the first step in glycogen synthesis by converting glucose-1-phosphate into ADP-Glucose, which is added in turn to a growing glycogen chain by glycogen synthases. Thus far, the in vitro study of GlgC were mainly performed using colorimetric or radiolabel-based phosphate release assays, limiting the option for analysing this reaction. With this work, we present a novel in vitro continuous assay coupling the ...

PFK-1 and PFK-2 were cloned and expressed in E. coli, purified, and kinetically characterised in terms of substrates and allosteric regulators.

The purified enzymes were kinetically charactyerised in terms of substrate sensitivity and alloestric regulation.

The experimental data for PFK-1 and PFK-2 were analysed and fitted with a MWC equation. The model is described in Mathematica and the plots in the manuscript are generatedin the notebook.

All data sets reflected by the figures in this work. Requires Graphpad Prism 7 (or later) to access. A trial version can be downloaded from the Graphpad prism website ( https://www.graphpad.com/demos/ )

Selected data sets from the main figures presented in this work.

Experimental data for kinetic characterisaton of PFK-1 and PFK-2.

Analysis of the sequences of PGM1 from several Synechocystis strains revealed a different annotation for Synechocystis sp. PCC 6803, which included a 16-amino acid N-terminal extension that is missing in the other strains. Additionally, the experimentally validated transcriptional start site from Synechocystis sp. PCC 6803 suggests a shorter open reading frame for PGM1, with Met 17 as putative translational start site. To clarify if the N-terminal extension is an annotation error, we prepared ...

To test the effecf of phosphorylation of Ser 47 on PGM1 activity, this residue was exchanged for Ala and Asp and the activity of the recombinant proteins was measured in vitro.

Mathematic notebook for enzyme kinetic analysis and model fit, including figure generation for manuscript.