Inorganic phosphate regulates CryIVA protoxin expression in Bacillus thuringiensis israelensis.
The role of nutritional factors during CryIVA protoxin expression in Bacillus thuringiensis israelensis (Bti) has been investigated. Inorganic phosphate (Pi) was found to stimulate 135 kD protoxin synthesis by Bti cells. There was a corresponding increase in the cryIVA specific mRNA in the presence of Pi. Inorganic phosphate inhibited HPr kinase but activated HPr phosphatase, the two enzymes responsible for regulating the concentration of phosphorylated HPr in the cell. Addition of protein phosphatase inhibitors NaF and calyculin A during resuspension resulted in the inhibition of toxin synthesis by Bti cells. Calyculin A inhibited HPr phosphatase activity in the in vitro assay also. The concentration of phosphorylated HPr was upregulated when the cells were resuspended in the presence of calyculin A, while the levels of the same were lowered in the presence of Pi, as determined by Western blotting the respective cells. The efficiency of sporulation of Bti was not affected when Pi was added alone or along with the phosphatase inhibitor calyculin A.
Banerjee-Bhatnagar
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International Center For Genetic Engineering and Biotechnology, New Delhi, 110067, India. nirupama@icgeb.res.in
D001413:Bacillus thuringiensis / Q000187:drug effects*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics; D004731:Endotoxins; D004789:Enzyme Activation; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins; D007306:Insecticides / Q000378:metabolism; D008387:Marine Toxins; D010080:Oxazoles / Q000494:pharmacology; D010710:Phosphates / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011498:Protein Precursors / Q000096:biosynthesis* / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012969:Sodium Fluoride / Q000494:pharmacology
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; D008387:Marine Toxins; D010080:Oxazoles; D010710:Phosphates; D011498:Protein Precursors; C030956:insecticidal crystal protein, Bacillus Thuringiensis; C059041:calyculin A; D012969:Sodium Fluoride; C110847:HPr kinase; D017346:Protein Serine-Threonine Kinases; C110846:YvoE protein, Bacillus substilis; D010749:Phosphoprotein Phosphatases