{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T23:34:34Z","timestamp":1790638474702,"version":"4.1.0"},"reference-count":50,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2021,5,7]],"date-time":"2021-05-07T00:00:00Z","timestamp":1620345600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100009081","name":"Institut National des Sciences Appliqu\u00e9es de Lyon","doi-asserted-by":"publisher","award":["ANR-17-CE20-0031-01"],"award-info":[{"award-number":["ANR-17-CE20-0031-01"]}],"id":[{"id":"10.13039\/501100009081","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Peptidoglycan recognition proteins (PGRPs) are ubiquitous among animals and play pivotal functions in insect immunity. Non-catalytic PGRPs are involved in the activation of immune pathways by binding to the peptidoglycan (PGN), whereas amidase PGRPs are capable of cleaving the PGN into non-immunogenic compounds. Drosophila PGRP-LB belongs to the amidase PGRPs and downregulates the immune deficiency (IMD) pathway by cleaving meso-2,6-diaminopimelic (meso-DAP or DAP)-type PGN. While the recognition process is well analyzed for the non-catalytic PGRPs, little is known about the enzymatic mechanism for the amidase PGRPs, despite their essential function in immune homeostasis. Here, we analyzed the specific activity of different isoforms of Drosophila PGRP-LB towards various PGN substrates to understand their specificity and role in Drosophila immunity. We show that these isoforms have similar activity towards the different compounds. To analyze the mechanism of the amidase activity, we performed site directed mutagenesis and solved the X-ray structures of wild-type Drosophila PGRP-LB and its mutants, with one of these structures presenting a protein complexed with the tracheal cytotoxin (TCT), a muropeptide derived from the PGN. Only the Y78F mutation abolished the PGN cleavage while other mutations reduced the activity solely. Together, our findings suggest the dynamic role of the residue Y78 in the amidase mechanism by nucleophilic attack through a water molecule to the carbonyl group of the amide function destabilized by Zn2+.<\/jats:p>","DOI":"10.3390\/ijms22094957","type":"journal-article","created":{"date-parts":[[2021,5,7]],"date-time":"2021-05-07T10:06:12Z","timestamp":1620381972000},"page":"4957","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["PGRP-LB: An Inside View into the Mechanism of the Amidase Reaction"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6933-2287","authenticated-orcid":false,"given":"Julien","family":"Orlans","sequence":"first","affiliation":[{"name":"Univ Lyon, INSA Lyon, INRAE, BF2I, UMR 203, 69621 Villeurbanne, France"},{"name":"Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6377-5573","authenticated-orcid":false,"given":"Carole","family":"Vincent-Monegat","sequence":"additional","affiliation":[{"name":"Univ Lyon, INSA Lyon, INRAE, BF2I, UMR 203, 69621 Villeurbanne, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Isabelle","family":"Rahioui","sequence":"additional","affiliation":[{"name":"Univ Lyon, INSA Lyon, INRAE, BF2I, UMR 203, 69621 Villeurbanne, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Catherine","family":"Sivignon","sequence":"additional","affiliation":[{"name":"Univ Lyon, INSA Lyon, INRAE, BF2I, UMR 203, 69621 Villeurbanne, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5227-4770","authenticated-orcid":false,"given":"Agata","family":"Butryn","sequence":"additional","affiliation":[{"name":"Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK"},{"name":"Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0488-550X","authenticated-orcid":false,"given":"Laurent","family":"Soul\u00e8re","sequence":"additional","affiliation":[{"name":"Univ Lyon, INSA Lyon, Universit\u00e9 Claude Bernard Lyon 1, CPE Lyon, UMR 5246, CNRS, ICBMS, Institut de Chimie et de Biochimie Mol\u00e9culaires et Supramol\u00e9culaires, B\u00e2t. E. Lederer, 1 rue Victor Grignard, 69622 Villeurbanne, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2550-1752","authenticated-orcid":false,"given":"Anna","family":"Zaidman-Remy","sequence":"additional","affiliation":[{"name":"Univ Lyon, INSA Lyon, INRAE, BF2I, UMR 203, 69621 Villeurbanne, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Allen M.","family":"Orville","sequence":"additional","affiliation":[{"name":"Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK"},{"name":"Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abdelaziz","family":"Heddi","sequence":"additional","affiliation":[{"name":"Univ Lyon, INSA Lyon, INRAE, BF2I, UMR 203, 69621 Villeurbanne, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pierre","family":"Aller","sequence":"additional","affiliation":[{"name":"Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK"},{"name":"Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pedro","family":"Da Silva","sequence":"additional","affiliation":[{"name":"Univ Lyon, INSA Lyon, INRAE, BF2I, UMR 203, 69621 Villeurbanne, France"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,5,7]]},"reference":[{"key":"ref_1","first-page":"127","article-title":"Peptidoglycan","volume":"Volume 92","author":"Kuhn","year":"2019","journal-title":"Bacterial Adhesion"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Vollmer, W. 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