An increase in the level of 2-oxoglutarate promotes heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120.
In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, a starvation of combined nitrogen induces differentiation of heterocysts, cells specialized in nitrogen fixation. How do filaments perceive the limitation of the source of combined nitrogen, and what determines the proportion of heterocysts? In cyanobacteria, 2-oxoglutarate provides a carbon skeleton for the incorporation of inorganic nitrogen. Recently, it has been proposed that the concentration of 2-oxoglutarate reflects the nitrogen status in cyanobacteria. To investigate the effect of 2-oxoglutarate on heterocyst development, a heterologous gene encoding a 2-oxoglutarate permease under the control of a regulated promoter was expressed in Anabaena sp. PCC 7120. The increase of 2-oxoglutarate within cells can trigger heterocyst differentiation in a subpopulation of filaments even in the presence of nitrate. In the absence of a source of combined nitrogen, it can increase heterocyst frequency, advance the timing of commitment to heterocyst development and further increase the proportion of heterocysts in a patS mutant. Here, it is proposed that the intracellular concentration of 2-oxoglutarate is involved in the determination of the proportion of the two cell types according to the carbon/nitrogen status of the filament.
Li
Jian-Hong
JH
Laboratoire de Chimie Bactérienne, IBSM, CNRS 31, chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
Laurent
Sophie
S
Laboratoire de Chimie Bactérienne, IBSM, CNRS 31, chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
Konde
Viren
V
Laboratoire de Chimie Bactérienne, IBSM, CNRS 31, chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
Bédu
Sylvie
S
Laboratoire de Chimie Bactérienne, IBSM, CNRS 31, chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
Zhang
Cheng-Cai
CC
Key Laboratory of Agromicrobiology, Huazhong Agriculture University, 430070 Wuhan, Hubei, People's Republic of China.|Laboratoire de Chimie Bactérienne, IBSM, CNRS 31, chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
D017033:Anabaena / Q000254:growth & development / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics; D001692:Biological Transport; D029382:Dicarboxylic Acid Transporters / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics; D007656:Ketoglutaric Acids / Q000378:metabolism*; D007700:Kinetics; D011401:Promoter Regions, Genetic
D001426:Bacterial Proteins; D029382:Dicarboxylic Acid Transporters; D029968:Escherichia coli Proteins; D007656:Ketoglutaric Acids; C068628:KgtP protein, E coli