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PMID:12496260
| Citation |
Mellroth, P, Karlsson, J and Steiner, H (2003) A scavenger function for a Drosophila peptidoglycan recognition protein. J. Biol. Chem. 278:7059-64 |
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| Abstract |
Recent studies of peptidoglycan recognition protein (PGRP) have shown that 2 of the 13 Drosophila PGRP genes encode proteins that function as receptors mediating immune responses to bacteria. We show here that another member, PGRP-SC1B, has a totally different function because it has enzymatic activity and thereby can degrade peptidoglycan. A mass spectrometric analysis of the cleavage products demonstrates that the enzyme hydrolyzes the lactylamide bond between the glycan strand and the cross-linking peptides. This result assigns the protein as an N-acetylmuramoyl-l-alanine amidase (EC ), and the corresponding gene is thus the first of this class to be described from a eukaryotic organism. Mutant forms of PGRP-SC1B lacking a potential zinc ligand are enzymatically inactive but retain their peptidoglycan affinity. The immunostimulatory properties of PGRP-SC1B-degraded peptidoglycan are much reduced. This is in striking contrast to lysozyme-digested peptidoglycan, which retains most of its elicitor activity. This points toward a scavenger function for PGRP-SC1B. Furthermore, a sequence homology comparison with phage T7 lysozyme, also an N-acetylmuramoyl-l-alanine amidase, shows that as many as six of the Drosophila PGRPs could belong to this class of proteins. |
| Links |
PubMed Online version:10.1074/jbc.M208900200 |
| Keywords |
Animals; Anti-Bacterial Agents/pharmacology; Binding Sites; Blotting, Northern; Carrier Proteins/metabolism; Carrier Proteins/physiology; Cell Line; Chromatography, High Pressure Liquid; Cross-Linking Reagents/pharmacology; DNA, Complementary/metabolism; Drosophila/metabolism; Hydrolysis; Insects; Kinetics; Ligands; Mass Spectrometry; Muramidase/metabolism; Mutation; N-Acetylmuramoyl-L-alanine Amidase/chemistry; N-Acetylmuramoyl-L-alanine Amidase/metabolism; Peptides/chemistry; Peptidoglycan/metabolism; Protein Binding; RNA/metabolism; Recombinant Proteins/metabolism; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Time Factors; Zinc/chemistry |
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Significance
Annotations
| Gene product | Qualifier | GO ID | GO term name | Evidence Code | with/from | Aspect | Notes | Status |
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