title: PGRP-SB1: an N-acetylmuramoyl L-alanine amidase with antibacterial activity.
abstract: The peptidoglycan recognition protein (PGRP) family is conserved from insects to mammals and is involved in immune regulation and bacterial clearance. They form at least three functional classes; receptors required for immune gene expression; amidases that degrade peptidoglycan and scavenge the tissues from immune-stimulating peptidoglycan; and as proteins with antibacterial activity. We here report that PGRP-SB1 is an N-acetylmuramoyl l-alanine amidase, which (in contrast to the previously described PGRP-amidases) shows antibacterial activity. PGRP-SB1 is highly active against peptidoglycans that have a diaminopimelic acid (DAP) residue in the cross-linking peptide, but lack activity to most lysine-containing peptidoglycans. The antibacterial activity is pronounced against Bacillus megaterium with an LD(50) of 1.5microg ml(-1). The bactericidal effect of PGRP-SB1 is dependent on its enzymatic activity, as the zinc co-factor is essential. The bactericidal mode of action is thus different from non-enzymatic vertebrate PGRPs that have been reported to be antibacterial.
authors.affiliation: Department of Genetics, Microbiology, and Toxicology, Stockholm University, S-106 91 Stockholm, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Mellroth
authors.forename: Håkan
authors.initials: H
authors.lastname: Steiner
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D001410:Bacillus megaterium / Q000166:cytology* / Q000187:drug effects*; D002352:Carrier Proteins / Q000008:administration & dosage*; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D029721:Drosophila Proteins / Q000008:administration & dosage*
chemical_list: D000900:Anti-Bacterial Agents; D002352:Carrier Proteins; D029721:Drosophila Proteins; C118897:peptidoglycan recognition protein