Characterization of Three L-Asparaginases from Maritime Pine (Pinus pinaster Ait.)

Kinetics characterization of a low immunogenic recombinant l-asparaginase from Phaseolus vulgaris with cytotoxic activity against leukemia cells

l-asparaginases play a crucial role in the treatment of acute lymphoblastic leukemia (ALL), a type of cancer that mostly affects children and teenagers. However, it is common for these molecules to cause adverse reactions during treatment. These downsides ignite the search for novel asparaginases to mitigate these problems. Thus, this work aimed to produce and characterize a recombinant asparaginase from Phaseolus vulgaris (Asp-P). In this study, Asp-P was expressed in Escherichia coli with high yields and optimum activity at 40 °C, pH 9.0. The enzyme Km and Vmax values were 7.05 mM and 1027 U/mg, respectively. Asp-P is specific for l-asparagine, showing no activity against l-glutamine and other amino acids. The enzyme showed a higher cytotoxic effect against Raji than K562 cell lines, but only at high concentrations. In silico analysis indicated that Asp-P has lower immunogenicity than a commercial enzyme. Asp-P induced biofilm formation by Candida sp. due to sublethal dose, showing an underexplored potential of asparaginases. The absence of glutaminase activity, lower immunogenicity and optimal activity similar to physiological temperature conditions are characteristics that indicate Asp-P as a potential new commercial enzyme in the treatment of ALL and its underexplored application in the treatment of other diseases.

Identification of Metabolic Pathways Differentially Regulated in Somatic and Zygotic Embryos of Maritime Pine

Embryogenesis is a complex phase of conifer development involving hundreds of genes, and a proper understanding of this process is critical not only to produce embryos with different applied purposes but also for comparative studies with angiosperms. A global view of transcriptome dynamics during pine somatic and zygotic embryogenesis is currently missing. Here, we present a genome-wide transcriptome analysis of somatic and zygotic embryos at three developmental stages to identify conserved biological processes and gene functions during late embryogenesis. Most of the differences became more significant as the developmental process progressed from early to cotyledonary stages, and a higher number of genes were differentially expressed in somatic than in zygotic embryos. Metabolic pathways substantially affected included those involved in amino acid biosynthesis and utilization, and this difference was already observable at early developmental stages. Overall, this effect was found to be independent of the line (genotype) used to produce the somatic embryos. Additionally, transcription factors differentially expressed in somatic versus zygotic embryos were analyzed. Some potential hub regulatory genes were identified that can provide clues as to what transcription factors are controlling the process and to how the observed differences between somatic and zygotic embryogenesis in conifers could be regulated.

In silico characterization of a cyanobacterial plant-type isoaspartyl aminopeptidase/asparaginase

Asparaginases are found in a range of organisms, although those found in cyanobacteria have been little studied, in spite of their great potential for biotechnological application. This study therefore sought to characterize the molecular structure of an L-asparaginase from the cyanobacterium Limnothrix sp. CACIAM 69d, which was isolated from a freshwater Amazonian environment. After homology modeling, model validation was performed using a Ramachandran plot, VERIFY3D, and the RMSD. We also performed molecular docking and dynamics simulations based on binding free-energy analysis. Structural alignment revealed homology with the isoaspartyl peptidase/asparaginase (EcAIII) from Escherichia coli. When compared to the template, our model showed full conservation of the catalytic site. In silico simulations confirmed the interaction of cyanobacterial isoaspartyl peptidase/asparaginase with its substrate, β-Asp-Leu dipeptide. We also observed that the residues Thr154, Thr187, Gly207, Asp218, and Gly237 were fundamental to protein-ligand complexation. Overall, our results suggest that L-asparaginase from Limnothrix sp. CACIAM 669d has similar properties to E. coli EcAIII asparaginase. Our study opens up new perspectives for the biotechnological exploitation of cyanobacterial asparaginases.