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 language | English |
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Pages (from-to) | 5005-5014 |
Number of pages | 10 |
Journal | Embo Journal |
Volume | 25 |
Issue number | 20 |
DOIs | |
Publication status | Published - 18 Oct 2006 |
Keywords
- Drosophila
- Innate immunity
- Non-self-recognition