{
  "abstract": "Enterococcus faecalis is an opportunistic pathogen and facultative anaerobe that primarily relies on fermentative metabolism to colonize a wide range of aerobic and anaerobic environments. In the presence of exogenous heme, E. faecalis can assemble a minimal electron transport chain consisting of membrane-associated primary dehydrogenases, demethylmenaquinone, and the terminal cytochrome bd oxidase (CydAB). This respiratory chain is thought to generate a proton motive force to drive ATP synthesis via the F-type ATP synthase, thereby improving energy conservation under aerobic conditions. However, a cytosolic NADH oxidase (Nox) also consumes NADH and oxygen, potentially competing with the electron transport chain for reducing equivalents and terminal electron acceptors; but the relative physiological contributions of these two oxygen-reducing pathways remain poorly understood. To define the roles of CydAB and Nox under normoxic and hypoxic conditions, we constructed {Delta}cydAB and {Delta}nox mutants. Real-time, in situ measurements revealed {Delta}cydAB had no significant effect on oxygen utilization while in the {Delta}nox it was significantly reduced; revealing Nox as the major consumer of oxygen. Semi-untargeted metabolomic analysis further revealed oxidase-specific alterations in central metabolism with the {Delta}nox causing pronounced shifts in the ATP and NADH ratios; highlighting Nox as a key determinant of intracellular redox and energy homeostasis. Finally, single-cell fluorescence microscopy showed that membrane potential, a component of proton motive force, was substantially diminished only in the absence of both CydAB and Nox, or the F-type ATP synthase. These findings indicate that the F-type ATP synthase is a major generator of proton motive force, even upon aerobic growth, and demonstrate a complementary role for the electron transport chain and Nox in the bioenergetics of E. faecalis.",
  "abstract_shown": true,
  "affiliations": [
    "Newcastle University"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 11,
  "authors": [
    {
      "name": "O. Paxie"
    },
    {
      "name": "B. Nijagal"
    },
    {
      "name": "F. O. Todd Rose"
    },
    {
      "name": "S. Gastrell"
    },
    {
      "name": "S. Su"
    },
    {
      "name": "A. Saleh"
    },
    {
      "name": "J. W. Grimshaw"
    },
    {
      "name": "K. Rhee"
    },
    {
      "name": "H. Strahl"
    },
    {
      "name": "G. M. Cook"
    },
    {
      "affs": [
        0
      ],
      "name": "R. L. Darnell"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8tk2ekc78kccc.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.08.30.748090",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.08.30.748090v1.full",
  "id": "8tk2ekc78kccc",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.08.30.748090v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "microbiology"
    ],
    [
      "openalex",
      "1311|Bacterial Genetics and Biotechnology"
    ]
  ],
  "openalex": "W7204871762",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.08.30.748090v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/8tk2ekc78kccc.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:38Z",
      "native_id": "10.64898/2026.08.30.748090",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.08.30.748090v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "biorxiv:microbiology",
      "subfield": "microbiology"
    }
  ],
  "title": "Defining the role of aerobic respiration in the metabolism and bioenergetics of Enterococcus faecalis",
  "title_text": "Defining the role of aerobic respiration in the metabolism and bioenergetics of Enterococcus faecalis",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:38Z",
  "url": "https://research.draconitic.com/paper/8tk2ekc78kccc",
  "venue": "bioRxiv",
  "versions": []
}