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From Proteopedia
Drosophila Peptidoglycan Recognition Protein (PGRP)-SA
Structural highlights
FunctionPGPSA_DROME Peptidoglycan-recognition protein that plays a key role in innate immnunity by binding to peptidoglycans (PGN) of Gram-positive bacteria and activating the Toll pathway. Has no activity against on Gram-negative bacteria and fungi. Shows some partial redundancy with PRPGP-SD in Gram-positive bacteria recognition. May act by forming a complex with GNBP1 that activates the proteolytic cleavage of Spatzle and the subsequent activation of Toll pathway. Binds to diaminopimelic acid-type tetrapeptide PGN (DAP-type PGN) and lysine-type PGN (Lys-type PGN). Has some L,D-carboxypeptidase activity for DAP-type PGN, which are specific to prokaryotes, but not for Lys-type PGN.[1] [2] [3] [4] 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 PubMedPeptidoglycan recognition proteins (PGRPs) form a recently discovered protein family, which is conserved from insect to mammals and is implicated in the innate immune system by interacting with/or degrading microbial peptidoglycans (PGNs). Drosophila PGRP-SA is a member of this family of pattern recognition receptors and is involved in insect Toll activation. We report here the crystal structure of PGRP-SA at 1.56 A resolution, which represents the first example of a "recognition" PGRP. Comparison with the catalytic Drosophila PGRP-LB reveals an overall structure conservation with an L-shaped hydrophilic groove that is likely the PGN carbohydrate core binding site, but further suggests some possible functional homology between recognition and catalytic PGRPs. Consistent with sequence analysis, PGRP-SA does not contain the canonical zinc-binding residues found in catalytic PGRPs. However, substitution of the zinc-binding cysteine residue by serine, along with an altered coordinating histidine residue, assembles a constellation of residues that resembles a modified catalytic triad. The serine/histidine juxtaposition to a threonine residue and a carbonyl oxygen atom, along with conservation of the catalytic water molecule found in PGRP-LB, tantalizingly suggests some hydrolytic function for this member of receptor PGRPs. Crystal structure of the Drosophila peptidoglycan recognition protein (PGRP)-SA at 1.56 A resolution.,Reiser JB, Teyton L, Wilson IA J Mol Biol. 2004 Jul 16;340(4):909-17. PMID:15223330[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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