AI Summary & Key Takeaways
AI InsightThese results suggested thatchanges in polyP concentration cause a general stress condition inside the cell, which in turn stimulates secondary metabolite synthesis.
📌 3 Key Takeaways
Abstract
Polyphosphate polymer (polyP) plays a very important role in every living cell. Synthesis of this linear polymer of phosphate(Pi) residues is catalyzed by the polyphosphate kinase (PPK) enzyme. It was shown that high levels of intracellular polyphosphatestimulated endotoxin production by Bacillus thuringiensis subsp. israelensis (Bti). In this study, proteomic analysis of the wild-typeand two mutant strains, overexpressing the ppk gene (Bti pHTppk) and without the ppk gene (Bti ∆ppk), were used to clarify therelation between polyP and endotoxin production. Intracellular proteins were separated by two-dimensional gel electrophoresis; 41spots of interest (proteins differentially expressed) were obtained and 35 of them were identified by mass spectrometry. Analysis of theprotein profiles showed that there is a general decrease in the expression levels of proteins related with energy metabolism, amino acidmetabolism, and purine biosynthesis in both Bti pHTppk and Bti ∆ppk. Gluconeogenesis and fatty acid metabolism were also sloweddown in both strains, whereas expression of stress response proteins increased compared to the wild-type. These results suggested thatchanges in polyP concentration cause a general stress condition inside the cell, which in turn stimulates secondary metabolite synthesis.