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.
BuikemaW. J.,
HaselkornR.2001; Expression of the Anabaena hetR gene from a copper-regulated promoter leads to heterocyst differentiation under repressing conditions. Proc Natl Acad Sci U S A 98:2729–2734
Fadi AldehniM.,
SauerJ.,
SpielhaupterC.,
SchmidR.,
ForchhammerK.2003; Signal transduction protein PII is required for NtcA-regulated gene expression during nitrogen deprivation in the cyanobacterium Synechococcus elongatus strain PCC 7942. J Bacteriol 185:2582–2591
ForchhammerK.,
HedlerA.1997; Phosphoprotein PII from cyanobacteria – analysis of functional conservation with the PII signal-transduction protein from Escherichia coli. Eur J Biochem 244:869–875
ForchhammerK.,
Tandeau de MarsacN.1995; Phosphorylation of the PII protein ( glnB gene product) in the cyanobacterium Synechococcus sp. strain PCC 7942: analysis of the in vitro kinase activity. J Bacteriol 177:5812–5817
FriasJ. E.,
FloresE.,
HerreroA.1994; Requirement of the regulatory protein NtcA for the expression of nitrogen assimilation and heterocyst development genes in the cyanobacterium Anabaena sp. PCC 7120. Mol Microbiol 14:823–832
GhassemianM.,
WongB.,
FerreiraF.,
MarkleyJ. L.,
StrausN. A.1994; Cloning, sequencing and transcriptional studies of the genes for cytochrome c-553 and plastocyanin from Anabaena sp. PCC 7120. Microbiology 140:1151–1159
HansonT. E.,
ForchhammerK.,
Tandeau de MarsacN.,
MeeksJ. C.1998; Characterization of the glnB gene product of Nostoc punctiforme strain ATCC 29133: glnB or the PII protein may be essential. Microbiology 144:1537–1547
IrmlerA.,
SannerS.,
DierksH.,
ForchhammerK.1997; Dephosphorylation of the phosphoprotein PII in Synechococcus PCC 7942: identification of an ATP and 2-oxoglutarate-regulated phosphatase activity. Mol Microbiol 26:81–90
KanekoT.,
NakamuraY.,
WolkC. P.19 other authors2001; Complete genomic sequence of the filamentous nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120. DNA Res 8:205–213
LeeH.-M.,
Vazquez-BermudezM. F.,
Tandeau de MarsacN.1999; The global nitrogen regulator NtcA regulates transcription of the signal transducer PII (GlnB) and influences its phosphorylation level in response to nitrogen and carbon supplies in the cyanobacterium Synechococcus sp. strain PCC 7942. J Bacteriol 181:2697–2702
LeeM. H.,
SchererM.,
RigaliS.,
GoldenJ. W.2003; PlmA, a new member of the GntR family, has plasmid maintenance functions in Anabaena sp. strain PCC 7120. J Bacteriol 185:4315–4325
Martin-FigueroaE.,
NavarroF.,
FlorencioF. J.2000; The GS–GOGAT pathway is not operative in the heterocysts. Cloning and expression of the glsF gene from the cyanobacterium Anabaena sp. PCC 7120. FEBS Lett 476:282–286
MeeksJ. C.,
ElhaiJ.2002; Regulation of cellular differentiation in filamentous cyanobacteria in free-living and plant-associated symbiotic growth states. Microbiol Mol Biol Rev 66:94–121
Muro-PastorA. M.,
ValladaresA.,
FloresE.,
HerreroA.2002; Mutual dependence of the expression of the cell differentiation regulatory protein HetR and the global nitrogen regulator NtcA during heterocyst development. Mol Microbiol 44:1377–1385
NinfaA. J.,
JiangP.,
AtkinsonM. R.,
PeliskaJ. A.2000; Integration of antagonistic signals in the regulation of nitrogen assimilation in Escherichia coli. Curr Top Cell Regul 36:31–75
Paz-YepesJ.,
FloresE.,
HerreroA.2003; Transcriptional effects of the signal transduction protein PII ( glnB gene product) on NtcA-dependent genes in Synechococcus sp. PCC 7942. FEBS Lett 543:42–46
RuppertU.,
IrmlerA.,
KloftN.,
ForchhammerK.2002; The novel protein phosphatase PphA from Synechocystis PCC 6803 controls dephosphorylation of the signaling protein PII. Mol Microbiol 44:855–864
SeniorP. J.1975; Regulation of nitrogen metabolism in Escherichia coli and Klebsiella aerogenes: studies with the continuous-culture technique. J Bacteriol 123:407–418
TanigawaR.,
ShirokaneM.,
Maeda SiS.,
OmataT.,
TanakaK.,
TakahashiH.2002; Transcriptional activation of NtcA-dependent promoters of Synechococcus sp. PCC 7942 by 2-oxoglutarate in vitro. Proc Natl Acad Sci U S A 99:4251–4255
Vazquez-BermudezM. F.,
HerreroA.,
FloresE.2000; Uptake of 2-oxoglutarate in Synechococcus strains transformed with the Escherichia colikgtP gene. J Bacteriol 182:211–215
Vazquez-BermudezM. F.,
HerreroA.,
FloresE.2002; 2-Oxoglutarate increases the binding affinity of the NtcA (nitrogen control) transcription factor for the Synechococcus glnA promoter. FEBS Lett 512:71–74
Vazquez-BermudezM. F.,
HerreroA.,
FloresE.2003; Carbon supply and 2-oxoglutarate effects on expression of nitrate reductase and nitrogen-regulated genes in Synechococcus sp. strain PCC 7942. FEMS Microbiol Lett 221:155–159
WolkC. P.2000; Heterocyst formation in Anabaena. In Prokaryotic Development pp 83–104 Edited by
BrunY. V.,
ShimketsL. J.
Washington, DC: American Society for Microbiology;
WolkC. P.,
ErnstA.,
ElhaiJ.1994; Heterocyst metabolism and development. In The Molecular Biology of Cyanobacteria pp 769–823 Edited by
BryantD. A.
Dordrecht: Kluwer;
ZhangC.-C.1993; A gene encoding a protein related to eukaryotic protein kinases from the filamentous heterocystous cyanobacterium Anabaena PCC 7120. Proc Natl Acad Sci U S A 90:11840–11844
ZhangC.-C.,
DurandM.-C.,
JeanjeanR.,
JosetF.1989; Molecular and genetical analysis of the fructose-glucose transport system in the cyanobacterium Synechocystis PCC6803. Mol Microbiol 3:1221–1229