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ORIGINAL RESEARCH article

Front. Cell. Infect. Microbiol.
Sec. Antibiotic Resistance and New Antimicrobial drugs
Volume 15 - 2025 | doi: 10.3389/fcimb.2025.1522114

Discovery of Amino Acid Substitutions in Penicillin-Binding Proteins Associated with Adaptation to D-Ala-D-Lac in Vancomycin-resistant Enterococcus faecalis

Provisionally accepted
NESE CAGLAYAN NESE CAGLAYAN 1BANU SANCAK BANU SANCAK 2ZEYNEP KANLIDERE ZEYNEP KANLIDERE 3*TANIL KOCAGOZ TANIL KOCAGOZ 1,4*
  • 1 Institute of Health Sciences, Department of Medical Biotechnology, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
  • 2 School of Medicine, Department of Medical Microbiology, Hacettepe University, Ankara, Ankara, Türkiye
  • 3 Faculty of Pharmacy, Department of Basic Pharmaceutical Sciences, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
  • 4 School of Medicine, Department of Medical Microbiology, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye

The final, formatted version of the article will be published soon.

    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's effectiveness. However, how PBPswhich 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 vancomycinsusceptible and -resistant E. faecalis 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.

    Keywords: Vancomycin-resistance, Enterococci, Penicillin binding protein, Penicillin binding protein (PBP), Bacterial cell wall, Peptidoglycan, Penicillin-binding protein

    Received: 03 Nov 2024; Accepted: 22 Jan 2025.

    Copyright: © 2025 CAGLAYAN, SANCAK, KANLIDERE and KOCAGOZ. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    ZEYNEP KANLIDERE, Faculty of Pharmacy, Department of Basic Pharmaceutical Sciences, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye
    TANIL KOCAGOZ, School of Medicine, Department of Medical Microbiology, Acibadem Mehmet Ali Aydinlar University, Istanbul, Türkiye

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.