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Crystal structure of human peptidoglycan recognition protein Iα bound to a muramyl pentapeptide from Gram‐positive bacteria
Author(s) -
Guan Rongjin,
Brown Patrick H.,
Swaminathan Chittoor P.,
Roychowdhury Abhijit,
Boons GeertJan,
Mariuzza Roy A.
Publication year - 2006
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.062077606
Subject(s) - peptidoglycan , pentapeptide repeat , tripeptide , pattern recognition receptor , biology , biochemistry , peptide , muramyl dipeptide , binding site , ligand (biochemistry) , stereochemistry , innate immune system , chemistry , receptor , enzyme , in vitro
Peptidoglycan recognition proteins (PGRPs) are pattern recognition receptors of the innate immune system that bind bacterial peptidoglycans (PGNs). We determined the crystal structure, to 2.1 Å resolution, of the C‐terminal PGN‐binding domain of human PGRP‐Iα in complex with a muramyl pentapeptide (MPP) from Gram‐positive bacteria containing a complete peptide stem (L‐Ala‐D‐isoGln‐L‐Lys‐D‐Ala‐D‐Ala). The structure reveals important features not observed previously in the complex between PGRP‐Iα and a muramyl tripeptide lacking D‐Ala at stem positions 4 and 5. Most notable are ligand‐induced structural rearrangements in the PGN‐binding site that are essential for entry of the C‐terminal portion of the peptide stem and for locking MPP in the binding groove. We propose that similar structural rearrangements to accommodate the PGN stem likely characterize many PGRPs, both mammalian and insect.