6CKH
Manduca sexta Peptidoglycan Recognition Protein-1
Summary for 6CKH
| Entry DOI | 10.2210/pdb6ckh/pdb |
| Descriptor | Peptidoglycan-recognition protein (2 entities in total) |
| Functional Keywords | pattern recognition receptor, peptidoglycan, innate immune system, immune system |
| Biological source | Manduca sexta (Tobacco hawkmoth) |
| Total number of polymer chains | 1 |
| Total formula weight | 20552.93 |
| Authors | |
| Primary citation | Hu, Y.,Cao, X.,Li, X.,Wang, Y.,Boons, G.J.,Deng, J.,Jiang, H. The three-dimensional structure and recognition mechanism of Manduca sexta peptidoglycan recognition protein-1. Insect Biochem.Mol.Biol., 108:44-52, 2019 Cited by PubMed Abstract: Peptidoglycan recognition proteins (PGRPs) recognize bacteria through their unique cell wall constituent, peptidoglycans (PGs). PGRPs are conserved from insects to mammals and all function in antibacterial defense. In the tobacco hornworm Manduca sexta, PGRP1 and microbe binding protein (MBP) interact with PGs and hemolymph protease-14 precursor (proHP14) to yield active HP14. HP14 triggers a serine protease network that produces active phenoloxidase (PO), Spätzle, and other cytokines to stimulate immune responses. PGRP1 binds preferentially to diaminopimelic acid (DAP)-PGs of Gram-negative bacteria and Gram-positive Bacillus and Clostridium species than Lys-PGs of other Gram-positive bacteria. In this study, we synthesized DAP- and Lys-muramyl pentapeptide (MPP) and monitored their associations with M. sexta PGRP1 by surface plasmon resonance. The K values (0.57 μM for DAP-MPP and 45.6 μM for Lys-MPP) agree with the differential recognition of DAP- and Lys-PGs. To reveal its structural basis, we produced the PGRP1 in insect cells and determined its structure at a resolution of 2.1 Å. The protein adopts a fold similar to those from other PGRPs with a classical L-shaped PG-binding groove. A unique loop lining the shallow groove suggests a different ligand-binding mechanism. In summary, this study provided new insights into the PG recognition by PGRPs, a critical first step that initiates the serine protease cascade. PubMed: 30905759DOI: 10.1016/j.ibmb.2019.03.001 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.1 Å) |
Structure validation
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