The Drosophila Toll-9 activates a constitutive antimicrobial defense

UMMS Affiliation

Program in Molecular Medicine and Department of Cell Biology

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Document Type



Alleles; Animals; Antifungal Agents; Cell Line; Drosophila; Drosophila Proteins; Escherichia coli; Gene Expression Regulation; Insect Proteins; Receptors, Cell Surface; Signal Transduction; Toll-Like Receptors; Transfection


Life Sciences | Medicine and Health Sciences


The Toll family of transmembrane proteins participates in signaling infection during the innate immune response. We analyzed the nine Drosophila Toll proteins and found that wild-type Toll-9 behaves similar to gain-of-function Toll-1. Toll-9 activates strongly the expression of drosomycin, and utilizes similar signaling components to Toll-1 in activating the antifungal gene. The predicted protein sequence of Toll-9 contains a tyrosine residue in place of a conserved cysteine, and this residue switch is critical for the high activity of Toll-9. The Toll-9 gene is expressed in adult and larval stages prior to microbial challenge, and the expression correlates with the high constitutive level of drosomycin mRNA in the animals. The results suggest that Toll-9 is a constitutively active protein, and implies its novel function in protecting the host by maintaining a substantial level of antimicrobial gene products to ward off the continuous challenge of microorganisms.

DOI of Published Version



EMBO Rep. 2002 Jan;3(1):82-7. Epub 2001 Dec 19. Link to article on publisher's site

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EMBO reports

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