Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Nature. 2001 Dec 13;414(6865):756-9.

Drosophila Toll is activated by Gram-positive bacteria through a circulating peptidoglycan recognition protein.

Author information

  • 1Institut de Biologie Moleculaire et Cellulaire, UPR 9022 du CNRS, 15 rue Rene Descartes, 67084 Strasbourg Cedex, France.

Abstract

Microbial infection activates two distinct intracellular signalling cascades in the immune-responsive fat body of Drosophila. Gram-positive bacteria and fungi predominantly induce the Toll signalling pathway, whereas Gram-negative bacteria activate the Imd pathway. Loss-of-function mutants in either pathway reduce the resistance to corresponding infections. Genetic screens have identified a range of genes involved in these intracellular signalling cascades, but how they are activated by microbial infection is largely unknown. Activation of the transmembrane receptor Toll requires a proteolytically cleaved form of an extracellular cytokine-like polypeptide, Spätzle, suggesting that Toll does not itself function as a bona fide recognition receptor of microbial patterns. This is in apparent contrast with the mammalian Toll-like receptors and raises the question of which host molecules actually recognize microbial patterns to activate Toll through Spätzle. Here we present a mutation that blocks Toll activation by Gram-positive bacteria and significantly decreases resistance to this type of infection. The mutation semmelweis (seml) inactivates the gene encoding a peptidoglycan recognition protein (PGRP-SA). Interestingly, seml does not affect Toll activation by fungal infection, indicating the existence of a distinct recognition system for fungi to activate the Toll pathway.

PMID:
11742401
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Nature Publishing Group Icon for Faculty of 1000
    Loading ...
    Write to the Help Desk