Lipid production and molecular dynamics simulation for regulation of accD gene in cyanobacteria under different N and P regimes

Abstract

BackgroundMicroalgae grown under different nutrient deficient conditions present a good source of natural lipids with applications for several types of biofuels. The expression of acetyl-CoA carboxylase gene can further provide an insight to the mechanisms leading to enhanced lipid production under such stresses. In this study, two nutrients viz. nitrogen and phosphorus were modulated to see its effect on lipid productivity in selected cyanobacteria and its correlation with Accase followed by molecular dynamics simulation.ResultsSelected cyanobacteria viz. Oscillatoria sp. (SP8), Anabaena sp. (SP12), Anabaena sp. (SP13), Microcoleus sp. (SP18), and Nostoc sp. (SP20) varied in their ability to accumulate lipids which ranged from a lowest of 0.13% in Anabaena sp. (SP13) to the maximum of 7.24% in Microcoleus sp. (SP18). Microcoleus sp. (SP18) also recorded highest lipid accumulation at both N (6 mM NaNO3) and P (0.20 mM K2HPO4) limiting conditions. The overall expression of accD was found to be upregulated in both Oscillatoria sp. (SP8) and Microcoleus sp. (SP18) for all nitrogen concentrations but was differentially regulated with both positive and negative induction under phosphorus stress conditions. Maximum induction was observed in Microcoleus sp. (SP18) at 0.20 mM K2HPO4. The obtained 3D structure of SP8 protein (21.8 kDa) showed six alpha helices, while SP18 protein (16.7 kDa) exhibited four alpha helices and four beta sheets. The phi (ϕ)/psi(ψ) angles of the amino acid residues observed in Ramachandran plot analysis showed that both SP8 and SP18 proteins were highly stable with more than 90% amino acids in allowed regions. The molecular dynamics simulation results also indicated the stability of ligand-bound protein complexes.ConclusionIt has been demonstrated that cyanobacterial isolates are affected differently by nutrient limitation leading to variation in their lipid productivity. The same has been revealed by the behavior of accD gene expression which was regulated more by nutrients concentrations rather than the organism. However, the ligand-bound protein complexes were stable throughout MD simulations.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0776-2) contains supplementary material, which is available to authorized users.

Molecular Analysis of Disease-Responsive Genes Revealing the Resistance Potential Against Fusarium Wilt (Fusarium udum Butler) Dependent on Genotype Variability in the Leguminous Crop Pigeonpea

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“…A study conducted by Gu et al [ 55 ] demonstrated that Scenedesmusacutus was found to be capable of assimilating nitrogen from LEA residuals and was able to replace nitrate in culturing media, thus facilitating nutrient recycling. Another recent study reports that nitrogen/phosphorus limitation in microalgae leads to variation in lipid productivity, which was validated by the expression of acetyl-CoA carboxylase gene [ 25 ].…”

“…The information about enzymes such as EC numbers, gene, protein, pathways and substrates is linked with the help of protein databases and its resources, viz. BRENDA [ 69 ] and ExPASy [ 25 ]. Visualization is an excellent approach for deeper understanding of pathways and reconstructed metabolic networks.…”

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