{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,12]],"date-time":"2026-09-12T16:51:36Z","timestamp":1789231896541,"version":"build-2803163510"},"reference-count":56,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,2,11]],"date-time":"2025-02-11T00:00:00Z","timestamp":1739232000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Cell. Infect. Microbiol."],"abstract":"<jats:p>The bacterial cell wall, essential for structural integrity, is synthesized with penicillin-binding proteins (PBPs). Vancomycin-resistant enterococci (VRE) evades vancomycin by replacing D-Ala-D-Ala in their cell wall precursors with D-Ala-D-Lac, reducing the drug\u2019s effectiveness. However, how PBPs-which typically use D-Ala-D-Ala as a substrate-adapt to recognize D-Ala-D-Lac remains unclear. Here, we performed Sanger sequencing and alignment of PBP genes from both vancomycin-susceptible and -resistant <jats:italic>E. faecalis<\/jats:italic> strains to identify mutations, following amplification by PCR. We then applied homology modeling to assess structural impacts of these changes on PBPs and conducted docking studies to investigate ligand-binding interactions. For the first time, we identified specific adaptations in certain VRE PBPs that may facilitate the D-Ala-D-Lac utilization. We found that PBP1B, PBP2A, PBP3 showed changes, while PBP1A, PBP2B and PBP4 remained unchanged. Notably, a threonine-to-asparagine substitution at location 491 in PBP1B leads to a shift in substrate preference from D-Ala-D-Ala to D-Ala-D-Lac. Similar structural changes in PBP3 suggest that the presence of changed and unchanged PBPs within the same classes suggests compensatory interactions, indicating a teamwork among multiple PBPs. These insights into PBPs provide a deeper understanding of D-Ala-D-Lac utilization in VRE, may be used to develop new therapeutic agents to combat vancomycin resistance.<\/jats:p>","DOI":"10.3389\/fcimb.2025.1522114","type":"journal-article","created":{"date-parts":[[2025,2,11]],"date-time":"2025-02-11T07:01:16Z","timestamp":1739257276000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":6,"title":["Discovery of amino acid substitutions in penicillin-binding proteins associated with adaptation to D-Ala-D-Lac in vancomycin-resistant Enterococcus faecalis"],"prefix":"10.3389","volume":"15","author":[{"given":"Nese","family":"Caglayan","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Banu","family":"Sancak","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zeynep","family":"Kanlidere","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tanil","family":"Kocagoz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,2,11]]},"reference":[{"key":"B1","unstructured":"2019 Antibiotic Resistance Threats Report\n          \n          2024"},{"key":"B2","doi-asserted-by":"publisher","first-page":"403","DOI":"10.1016\/S0022-2836(05)80360-2","article-title":"Basic local alignment search tool","volume":"215","author":"Altschul","year":"1990","journal-title":"J. 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