Peptidoglycan Recognition Proteins : Major Regulators of Drosophila Immunity

Abstract: All eukaryotic organisms have an innate immune system characterized by germ-line encoded receptors and effector molecules, which mediate detection and clearance of microbes such as bacteria, fungi, and parasites. VertebrateDrosophila as a genetically tractable organism with aThis thesis concerns the peptidoglycan recognition protein (PGRP) gene family in the fruit fly. The family consists of thirteen genes, of which a few have been reported to be part of the signaling pathways that regulates immuneData presented show that the putative receptors have affinity for peptidoglycan, but not for lipopolysaccharide, or the fungal cell wall polymer beta-glucan. PGRP-SA, receptor of the Toll pathway, has a preference forIn a search for novel PGRP receptors I found two PGRP proteins that instead displayed enzymatic activity towards peptidoglycan. They are of the N-actylmuramoyl L-alanine amidase type, which degrades peptidoglycan by splittingStaphylococcus aureus peptidoglycan looses its immune elicitor capacity. This is in contrast to lysozyme-degraded peptidoglycan, which isDrosophila PGRPs to be potential enzymes. PGRP-SB1 is the other enzymatic PGRP described within this thesis. It has a moreBacillus megaterium.In conclusion, receptor PGRP proteins binds bacterial peptidoglycan and triggers immune gene pathways and enzymatic PGRPs have the capacity to reduce the elicitor property of peptidoglycan.