Unraveling of cross talk between Ca²⁺ and ROS regulating enzymes in Anabaena 7120 and ntcA mutant

Abstract

In order to understand a cross talk between Ca(2+) and ROS regulating enzymes and the possible involvement of ntcA gene, Anabaena sp. PCC 7120 and its derivative ntcA mutant grown in varied levels of calcium chloride (0, 1, 10, and 100 mM) have been investigated. Scanning Electron Microscopy showed abnormal structure formation at high calcium concentration (100 mM) both in wild type and mutant. Fv /Fm values suggested that 100 mM calcium concentration was detrimental for photosynthetic apparatus. SOD, catalase, APX, GR, and peroxidase activity were found to be maximum for 100 mM and minimum for 1 mM of exogenously supplied calcium salt. NADPH contents were higher for wild type than mutant. RAPD-PCR and SDS-PAGE analysis revealed a difference in DNA as well as proteome pattern with changes in calcium chloride regime. Prominent bands of approximately 70, 33, 21, and 14 kDa expressed in the wild type served as the marker polypeptide bands under calcium supplementation. Results suggest that higher levels of calcium ion disturb the cellular homeostasis generating ROS, thereby inducing enhanced levels of antioxidative enzymes. Further, data also suggests possible involvement of ntcA gene in cross talk between calcium ion and ROS regulating enzymes.

Modulation of fatty acids and hydrocarbons inAnabaena7120 and itsntcAmutant under calcium

“…All the experiments were conducted in triplicate at the 8th day and repeated at least twice to confirm the reproducibility of the results. As already reported in our previous findings 1 mM CaCl 2 concentration was stimulatory while 10 mM CaCl 2 was the inhibitory concentration based on growth behaviour .…”

“…The results of the present investigation suggest that CaCl 2 levels affect biomass, carbohydrate, lipid, and protein content profoundly. Higher biomass and protein content at stimulatory concentration (1 mM) is probably due to higher chlorophyll a and lower levels of antioxidative enzymes which account for its growth at this concentration of calcium chloride . Higher carbohydrate content at inhibitory concentration suggest for involvement of sugars in osmotic regulation of cells during stress conditions.…”

The small Ca2+-binding protein CSE links Ca2+ signalling with nitrogen metabolism and filament integrity in Anabaena sp. PCC 7120

“…A transient increase in the intracellular Ca 2+ concentration ([Ca 2+ ] i ) from a resting level of about 0.2 μM up to 4 μM free Ca 2+ was observed upon light-to-dark transitions and during temperature, salt and osmotic stress [1][2][3]. The involvement of Ca 2+ has also been established in cyanobacterial growth [4], regulation of reactive oxygen species (ROS) [5], fine-tuning of the carbon (C) and nitrogen (N) balance [6,7], heat stress acclimation [8], exopolysaccharide production [9], and fatty acid and hydrocarbon composition [10].…”