Document Detail

Bacillus thuringiensis pore-forming toxins trigger massive shedding of GPI-anchored aminopeptidase N from gypsy moth midgut epithelial cells.
MedLine Citation:
PMID:  18510972     Owner:  NLM     Status:  MEDLINE    
The insecticidal Cry proteins produced by Bacillus thuringiensis strains are pore-forming toxins (PFTs) that bind to the midgut brush border membrane and cause extensive damage to the midgut epithelial cells of susceptible insect larvae. Force-feeding B. thuringiensis PFTs to Lymantria dispar larvae elicited rapid and massive shedding of a glycosylphosphatidylinositol (GPI)-anchored aminopeptidase N (APN) from midgut epithelial cells into the luminal fluid, and depletion of the membrane-anchored enzyme on the midgut epithelial cells. The amount of APN released into the luminal fluid of intoxicated larvae was dose- and time-dependent, and directly related to insecticidal potency of the PFTs. The induction of toxin-induced shedding of APN was inhibited by cyclic AMP and MAPK kinase (MEK) inhibitors PD98059 and U0126, indicating that signal transduction in the MEK/ERK pathway is involved in the regulation of the shedding process. APN released from epithelial cells appears to be generated by the action of a phosphatidylinositol-specific phospholipase C (PI-PLC) cleavage of the GPI anchor based upon detection of a cross-reacting determinant (CRD) on the protein shed into the luminal fluid. Alkaline phosphatase was also released from the gut epithelial cells, supporting the conclusion that other GPI-anchored proteins are released as a consequence of the activation PI-PLC. These observations are the basis of a novel and highly sensitive tool for evaluating the insecticidal activity of new Cry proteins obtained though discovery or protein engineering.
Algimantas P Valaitis
Publication Detail:
Type:  Journal Article     Date:  2008-03-20
Journal Detail:
Title:  Insect biochemistry and molecular biology     Volume:  38     ISSN:  0965-1748     ISO Abbreviation:  Insect Biochem. Mol. Biol.     Publication Date:  2008 Jun 
Date Detail:
Created Date:  2008-05-30     Completed Date:  2008-09-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9207282     Medline TA:  Insect Biochem Mol Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  611-8     Citation Subset:  IM    
USDA Forest Service, U.S. Department of Agriculture, 359 Main Road, Delaware, OH 43015, USA.
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MeSH Terms
Alkaline Phosphatase / metabolism
Antigens, CD13 / metabolism*
Bacterial Proteins / pharmacology*
Endotoxins / pharmacology*
Epithelial Cells / metabolism*
Gastrointestinal Tract / drug effects,  metabolism
Glycosylphosphatidylinositols / metabolism*
Hemolysin Proteins / pharmacology*
Larva / drug effects,  metabolism
Moths / drug effects*,  metabolism
Signal Transduction
Toxicity Tests
Type C Phospholipases / metabolism
Reg. No./Substance:
0/Bacterial Proteins; 0/Endotoxins; 0/Glycosylphosphatidylinositols; 0/Hemolysin Proteins; 0/insecticidal crystal protein, Bacillus Thuringiensis; EC Phosphatase; EC 3.1.4.-/Type C Phospholipases; EC, CD13

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