{
  "id": 18485524,
  "title": "Active site electrostatic effects modulate DBO inhibitor potency against OXA-48 variants",
  "url": "https://urgent.news/2026/11/06/active-site-electrostatic-effects-modulate-dbo-inhibitor-potency",
  "topic": "science",
  "section": "Science",
  "published": "2026-11-06T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.11.04.764282v1?rss=1"
  },
  "original_language": "en",
  "account": "OXA-48 class D{beta}-lactamases and their variants pose a significant threat due to their carbapenemase and cephalosporinase activity. New inhibitors, Diazabicyclooctanes (DBOs), are being developed to tackle these enzymes, but their potency varies depending on mutations. Specifically, nacubactam, a newer DBO, shows lower potency compared to avibactam against OXA-48 variants. This disparity is particularly notable when comparing OXA-48 to its variants OXA-163 and -405, which have mutations in the {beta}5-{beta}6 loop and prioritize cephalosporin degradation over carbapenems.\n\nMultiscale simulations reveal that the second step of DBO acylation is the rate-limiting process. QM/MM MD simulations demonstrate that nacubactam experiences a significantly higher energy barrier for covalent inhibition of OXA-48-like enzymes compared to avibactam. This difference is directly linked to variations in the active site's electric field due to DBO-specific changes. Additionally, simulations of non-covalent complexes suggest that nacubactam's lower potency towards OXA-48, as opposed to OXA-163 and -405, can be partly attributed to weaker binding. This is a result of electrostatic repulsion between the positively charged nacubactam tail and Arg214 in the {beta}5-{beta}6 loop.\n\nBy integrating computational predictions of covalent reaction rates and non-covalent binding affinities, the study accurately mirrors the experimental IC50 values and predicts potency against OXA-517, a newly identified OXA-48 variant with the capability to hydrolyze various antibiotics. This research not only offers insights into the mechanism of class D{beta}-lactamase inhibition but also uncovers the factors contributing to the differential potency of DBOs against OXA-48 variants, emphasizing the impact of subtle enzyme differences on inhibitory effects.",
  "summary": "The OXA-48 class D {beta}-lactamase and its variants are clinically concerning through their carbapenemase and cephalosporinase activity. Effective inhibitors are therefore urgently needed. Diazabicyclooctanes (DBOs) are newly introduced non {beta}-lactam based inhibitors, but their potency is affected by mutations, with the more recently developed nacubactam consistently less potent than…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}