Sensing of Gram-positive bacteria in Drosophila: GNBP1 is needed to process and present peptidoglycan to PGRP-SA

Lihui Wang, Alexander N R Weber, Magda L. Atilano, Sergio R. Filipe, Nicholas J. Gay, Petros Ligoxygakis

Research output: Contribution to journalArticle

69 Citations (Scopus)

Abstract

Genetic evidence indicates that Drosophila defense against Gram-positive bacteria is mediated by two putative pattern recognition receptors acting upstream of Toll, namely Gram-negative binding protein 1 (GNBP1) and peptidoglycan recognition protein SA (PGRP-SA). Until now however, the molecular recognition proceedings for sensing of Gram-positive pathogens were not known. In the present, we report the physical interaction between GNBP1 and PGRP-SA using recombinant proteins. GNBP1 was able to hydrolyze Gram-positive peptidoglycan (PG), while PGRP-SA bound highly purified PG fragments (muropeptides). Interaction between these proteins was enhanced in the presence of PG or muropeptides. PGRP-SA binding depended on the polymerization status of the muropeptides, pointing to constraints in the number of PGRP-SA molecules bound for signaling initiation. We propose a model whereby GNBP1 presents a processed form of PG for sensing by PGRP-SA and that a tripartite interaction between these proteins and PG is essential for downstream signaling.

Original languageEnglish
Pages (from-to)5005-5014
Number of pages10
JournalEmbo Journal
Volume25
Issue number20
DOIs
Publication statusPublished - 18 Oct 2006

Keywords

  • Drosophila
  • Innate immunity
  • Non-self-recognition

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