The novel P _II -interactor PirC identifies phosphoglycerate mutase as key control point of carbon storage metabolism in cyanobacteria

Significance In this work, we identified the regulatory mechanism of key control point cyanobacterial carbon metabolism, glycolytic phosphoglycerate mutase (PGAM) reaction, converting 3-PGA into 2-PGA and thereby exporting organic from photosynthetic Calvin cycle. We show that PGAM activity is controlled by a small modulator protein PirC (product sll0944 ), which inhibits enzyme through protein–protein interaction. The availability for inhibition pervasive carbon/nitrogen balance regulator P II , sequesters at low 2-oxoglutarate levels releases it high levels. PirC-mediated triggers glycogen accumulation, disrupting regulation allows redirection flux, decisive requirement transforming cyanobacteria green factories.