title: The Drosophila amidase PGRP-LB modulates the immune response to bacterial infection.
abstract: The Drosophila host defense against gram-negative bacteria is mediated by the Imd pathway upon sensing of peptidoglycan by the peptidoglycan recognition protein (PGRP)-LC. Here we report a functional analysis of PGRP-LB, a catalytic member of the PGRP family. We show that PGRP-LB is a secreted protein regulated by the Imd pathway. Biochemical studies demonstrate that PGRP-LB is an amidase that specifically degrades gram-negative bacteria peptidoglycan. In agreement with its amidase activity, PGRP-LB downregulates the Imd pathway. Hence, activation of PGRP-LB by the Imd pathway provides a negative feedback regulation to tightly adjust immune activation to infection. Our study also reveals that PGRP-LB controls the immune reactivity of flies to the presence of ingested bacteria in the gut. Our work highlights the key role of PGRPs that encode both sensors and scavengers of peptidoglycan, which modulate the level of the host immune response to the presence of infectious microorganisms.
authors.affiliation: Centre de Génétique Moléculaire du CNRS, F-91198 Gif-sur-Yvette, France.
authors.forename: Anna
authors.initials: A
authors.lastname: Zaidman-Rémy
authors.forename: Mireille
authors.initials: M
authors.lastname: Hervé
authors.forename: Mickael
authors.initials: M
authors.lastname: Poidevin
authors.forename: Sébastien
authors.initials: S
authors.lastname: Pili-Floury
authors.forename: Min-Sung
authors.initials: MS
authors.lastname: Kim
authors.forename: Didier
authors.initials: D
authors.lastname: Blanot
authors.forename: Byung-Ha
authors.initials: BH
authors.lastname: Oh
authors.forename: Ryu
authors.initials: R
authors.lastname: Ueda
authors.forename: Dominique
authors.initials: D
authors.lastname: Mengin-Lecreulx
authors.forename: Bruno
authors.initials: B
authors.lastname: Lemaitre
mesh_terms: D000818:Animals; D001424:Bacterial Infections / Q000276:immunology*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000276:immunology* / Q000378:metabolism*; D004330:Drosophila / Q000276:immunology*; D029721:Drosophila Proteins / Q000276:immunology* / Q000378:metabolism; D004789:Enzyme Activation / Q000276:immunology; D015870:Gene Expression; D018006:Myogenic Regulatory Factors / Q000276:immunology / Q000378:metabolism; D014157:Transcription Factors / Q000276:immunology / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D029721:Drosophila Proteins; D018006:Myogenic Regulatory Factors; D014157:Transcription Factors; C442328:lmd protein, Drosophila; C118897:peptidoglycan recognition protein