Calmodulin and calcium mediated regulation in prokaryotes

Onek, L. A.; Smith, Richard J.

doi:10.1099/00221287-138-6-1039

Cited by 84 publications

(43 citation statements)

References 81 publications

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“…However, growing evidence indicates that calcium might truly be involved in heterocyst development; in early studies Smith et al (1987) noted that the external concentration of Ca 2+ and the presence of several calcium agonists influenced heterocyst frequency in Nostoc PCC 6720. Later studies found a correlation between heterocyst frequency and different treatments that affect the accumulation of Ca 2+ in cells during the process of differentiation (Smith, 1988;Smith & Wilkins, 1988;Zhao et al, 1991;Onek & Smith, 1992), hence reinforcing the hypothesis that Ca 2+ might have a regulatory role in the differentiation of heterocysts.…”

Section: Introductionmentioning

confidence: 82%

A calcium signal is involved in heterocyst differentiation in the cyanobacterium Anabaena sp. PCC7120

et al. 2004

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The impact of calcium signals in virtually all cells has led to the study of their role in prokaryotic organisms as stress response modulators. Cell differentiation in adverse conditions is a common Ca2+-requiring response. Nitrogen starvation induces the differentiation of N2-fixing heterocysts in the filamentous cyanobacterium Anabaena sp. PCC7120. This paper reports the use of a recombinant strain of this organism expressing the photoprotein aequorin to monitor the intracellular free-calcium concentration during the course of heterocyst differentiation. A specific calcium signature that is triggered exclusively when cells are deprived of combined nitrogen and generated by intracellular calcium stores was identified. The intracellular calcium signal was manipulated by treatment with specific calcium drugs, and the effect of such manipulation on the process of heterocyst differentiation was subsequently assessed. Suppression, magnification or poor regulation of this signal prevented the process of heterocyst differentiation, thereby suggesting that a calcium signal with a defined set of kinetic parameters may be required for differentiation. A hetR mutant of Anabaena sp. PCC7120 that cannot differentiate into heterocysts retains, however, the capacity to generate the calcium transient in response to nitrogen deprivation, strongly suggesting that Ca2+ may be involved in a very early step of the differentiation process.

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Section: Introductionmentioning

confidence: 82%

A calcium signal is involved in heterocyst differentiation in the cyanobacterium Anabaena sp. PCC7120

et al. 2004

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“…In prokaryotic cells, an equivalent important role for Ca 2ϩ has been harder to demonstrate, but is now becoming clearer (Onek and Smith, 1992;Smith, 1995;Norris et al, 1996). However, the role(s) for Ca 2ϩ is still not well defined.…”

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confidence: 99%

Use of Recombinant Aequorin to Study Calcium Homeostasis and Monitor Calcium Transients in Response to Heat and Cold Shock in Cyanobacteria

et al. 2000

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We investigated the possibility of Ca 2ϩ signaling in cyanobacteria (blue-green algae) by measuring intracellular free Ca 2ϩ levels ([Ca 2ϩ ] i ) in a recombinant strain of the nitrogen fixing cyanobacterium Anabaena strain sp. PCC7120, which constitutively expresses the Ca 2ϩ -binding photoprotein apoaequorin. The homeostasis of intracellular Ca 2ϩ in response to increasing external Ca 2ϩ has been studied in this strain. The resting level of free Ca 2ϩ in Anabaena was found to be between 100 and 200 nm. Additions of increasing concentrations of external Ca 2ϩ gave a transient burst of [Ca 2ϩ ] i followed by a very quick decline, reaching a plateau within seconds that brought the level of [Ca 2ϩ ] i back to the resting value. These results indicate that Anabaena strain sp. PCC7120 is able to regulate its internal Ca 2ϩ levels. We also monitored Ca 2ϩ transients in our recombinant strain in response to heat and cold shock. The cell's response to both stresses was dependent on the way they were induced. The use of inhibitors suggests that heat shock mobilizes cytosolic Ca 2ϩ from both intracellular and extracellular sources, while the Ca 2ϩ source for cold shock signaling is mostly extracellular.

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“…Bacterial intracellular system of regulation of the concentration of inorganic ions appears to be an indispensable trait for competitive growth and survival in environments with a deficiency or excess of inorganic-ions (Silver and Walderhaug 1992). Though essential, Ca2+ often becomes toxic when present at high levels (Norris et al 1991;Onek and Smith 1992).…”

Section: Resultsmentioning

confidence: 99%

Comparison of root colonization by LR- and HR-isolates of fluorescent pseudomonads in soil with high salinity

Sakai

Ozawa

Futamata

et al. 1998

Soil Science and Plant Nutrition

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Calmodulin and calcium mediated regulation in prokaryotes

Cited by 84 publications

References 81 publications

A calcium signal is involved in heterocyst differentiation in the cyanobacterium Anabaena sp. PCC7120

A calcium signal is involved in heterocyst differentiation in the cyanobacterium Anabaena sp. PCC7120

Use of Recombinant Aequorin to Study Calcium Homeostasis and Monitor Calcium Transients in Response to Heat and Cold Shock in Cyanobacteria

Comparison of root colonization by LR- and HR-isolates of fluorescent pseudomonads in soil with high salinity

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