Role of calcium in acclimation of the cyanobacterium Synechococcus elongatus PCC 7942 to nitrogen starvation.

Abstract

A Ca2+ signal is required for the process of heterocyst differentiation in the filamentous diazotrophic cyanobacterium Anabaena sp. PCC 7120. This paper presents evidence that a transient increase in intracellular free Ca2+ is also involved in acclimation to nitrogen starvation in the unicellular non-diazotrophic cyanobacterium Synechococcus elongatus PCC 7942. The Ca2+ transient was triggered in response to nitrogen step-down or the addition of 2-oxoglutarate (2-OG), or its analogues 2,2-difluoropentanedioic acid (DFPA) and 2-methylenepentanedioic acid (2-MPA), to cells growing with combined nitrogen, suggesting that an increase in intracellular 2-OG levels precedes the Ca2+ transient. The signalling protein P(II) and the transcriptional regulator NtcA appear to be needed to trigger the signal. Suppression of the Ca2+ transient by the intracellular Ca2+ chelator N,N'-[1,2-ethanediylbis(oxy-2,1-phenylene)]bis[N-[2-[(acetyloxy)methoxy]-2-oxoethyl]]-,bis[(acetyloxy)methyl] ester (BAPTA-AM) inhibited expression of the glnB and glnN genes, which are involved in acclimation to nitrogen starvation and transcriptionally activated by NtcA. BAPTA-AM treatment partially inhibited expression of the nblA gene, which is involved in phycobiliprotein degradation following nutrient starvation and is regulated by NtcA and NblR; in close agreement, BAPTA-AM treatment partially inhibited bleaching following nitrogen starvation. Taken together, the results presented here strongly suggest an involvement of a defined Ca2+ transient in acclimation of S. elongatus to nitrogen starvation through NtcA-dependent regulation.

• Authors: Francisco Leganés, Karl Forchhammer, Francisca Fernández-Piñas
• Journal: Microbiology (Reading, England) (Microbiology (Reading)) Vol. 155 Issue Pt 1 Pg. 25-34 (Jan 2009) ISSN: 1350-0872 [Print] England
• PMID: 19118343 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Apoproteins
• Bacterial Proteins
• Calcium-Binding Proteins
• Culture Media
• Ketoglutaric Acids
• PII Nitrogen Regulatory Proteins
• Recombinant Proteins
• Transcription Factors
• apoaequorin
• Aequorin
• Sulfur
• Nitrogen
• Calcium

Topics

• Adaptation, Physiological
• Aequorin (metabolism)
• Apoproteins (metabolism)
• Bacterial Proteins (genetics, metabolism)
• Calcium (metabolism)
• Calcium-Binding Proteins (metabolism)
• Culture Media
• Gene Expression Regulation, Bacterial
• Heat-Shock Response
• Ketoglutaric Acids (metabolism)
• Mutation
• Nitrogen (metabolism)
• PII Nitrogen Regulatory Proteins (genetics, metabolism)
• Recombinant Proteins (metabolism)
• Sulfur (metabolism)
• Synechococcus (genetics, metabolism, physiology)
• Transcription Factors (metabolism)