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Crystal structure of the complex of peptidoglycan recognition protein (PGRP-S) with the PGN Fragment at 2.5 A resolution
Structural highlights
FunctionPGRP1_CAMDR Pattern receptor that binds to murein peptidoglycans (PGN) of Gram-positive bacteria. Has bactericidal activity towards Gram-positive bacteria. May kill Gram-positive bacteria by interfering with peptidoglycan biosynthesis. Binds also to Gram-negative bacteria. Involved in innate immunity. Is microbicidal for Gram-positive and Gram-negative bacteria and yeast. May function in intracellular killing of bacteria (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe peptidoglycan recognition protein PGRP-S is an innate immunity molecule that specifically interacts with microbial peptidoglycans and other pathogen-associated molecular patterns. We report here two structures of the unique tetrameric camel PGRP-S (CPGRP-S) complexed with (i) muramyl dipeptide (MDP) at 2.5 A resolution and (ii) GlcNAc and beta-maltose at 1.7A resolution. The binding studies carried out using surface plasmon resonance indicated that CPGRP-S binds to MDP with a dissociation constant of 10(-7) M, whereas the binding affinities for GlcNAc and beta-maltose separately are in the range of 10(-4) M to 10(-5) M, whereas the dissociation constant for the mixture of GlcNAc and maltose was estimated to be 10(-6) M. The data from bacterial suspension culture experiments showed a significant inhibition of the growth of Staphylococcus aureus cells when CPGRP-S was added to culture medium. The ELISA experiment showed that the amount of MDP-induced production of TNF-alpha and IL-6 decreased considerably after the introduction of CPGRP-S. The crystal structure determinations of (i) a binary complex with MDP and (ii) a ternary complex with GlcNAc and beta-maltose revealed that MDP, GlcNAc, and beta-maltose bound to CPGRP-S in the ligand binding cleft, which is situated at the interface of molecules C and D of the homotetramer formed by four protein molecules A, B, C, and D. In the binary complex, the muramyl moiety of MDP is observed at the C-D interface, whereas the peptide chain protrudes into the center of tetramer. In the ternary complex, GlcNAc and beta-maltose occupy distinct non-overlapping positions belonging to different subsites. Multiligand specificity of pathogen-associated molecular pattern-binding site in peptidoglycan recognition protein.,Sharma P, Dube D, Sinha M, Mishra B, Dey S, Mal G, Pathak KM, Kaur P, Sharma S, Singh TP J Biol Chem. 2011 Sep 9;286(36):31723-30. Epub 2011 Jul 22. PMID:21784863[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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