{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T16:13:55Z","timestamp":1778602435680,"version":"3.51.4"},"posted":{"date-parts":[[2026,5,8]]},"group-title":"Microbiology","reference-count":46,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T00:00:00Z","timestamp":1778198400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/www.biorxiv.org\/about\/FAQ#license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,5,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  <jats:italic>Francisella tularensis<\/jats:italic>\n                  is a highly infectious, Gram-negative intracellular bacterium and the causative agent of tularemia, a potentially fatal disease. Owing to its low infectious dose, ease of aerosolization, high virulence, lack of an effective vaccine, and potential use as a bioterrorism agent,\n                  <jats:italic>F. tularensis<\/jats:italic>\n                  is classified by the CDC as a Tier 1 Category A Select Agent. Despite its clinical importance, the mechanisms underlying\n                  <jats:italic>F. tularensis<\/jats:italic>\n                  virulence remain incompletely understood. In this study, we generated a partial Tn5 transposon insertion mutant library in the\n                  <jats:italic>F. tularensis<\/jats:italic>\n                  live vaccine strain (LVS) and identified a mutant disrupted in the\n                  <jats:italic>FTL_0690<\/jats:italic>\n                  gene through screening under macrophage-like conditions.\n                  <jats:italic>FTL_0690<\/jats:italic>\n                  encodes an acyl-CoA synthetase. Characterization of both a transposon-insertion mutant and a targeted deletion mutant (\u0394\n                  <jats:italic>FTL_0690<\/jats:italic>\n                  ) revealed critical roles for this enzyme in\n                  <jats:italic>F. tularensis<\/jats:italic>\n                  pathobiology. Loss of\n                  <jats:italic>FTL_0690<\/jats:italic>\n                  increased sensitivity to oxidative stress and impaired intracellular growth within macrophages compared to wild-type\n                  <jats:italic>F. tularensis<\/jats:italic>\n                  LVS. Lipidomic profiling of the \u0394\n                  <jats:italic>FTL_0690<\/jats:italic>\n                  mutant revealed disruptions in fatty acid metabolism, membrane lipid remodeling, and redox homeostasis. Altered lipid-derived and membrane-associated metabolites indicated defective phospholipid incorporation and altered membrane composition, likely contributing to oxidative stress sensitivity and reduced intramacrophage survival. Collectively, these findings demonstrate that\n                  <jats:italic>FTL_0690<\/jats:italic>\n                  which encodes long-chain acyl-CoA synthetase, contributes to lipid homeostasis, membrane integrity, and oxidative stress resistance of\n                  <jats:italic>F. tularensis<\/jats:italic>\n                  .\n                <\/jats:p>\n                <jats:sec>\n                  <jats:title>Importance<\/jats:title>\n                  <jats:p>\n                    This work addresses critical gaps in our understanding of\n                    <jats:italic>Francisella tularensis<\/jats:italic>\n                    virulence by identifying lipid metabolism as a central determinant of intracellular survival and stress resistance. By integrating transposon mutagenesis, targeted gene deletion, and lipidomic profiling, this study provides mechanistic insight into how metabolic remodeling supports pathogenesis. Our identification and characterization of\n                    <jats:italic>FTL_0690<\/jats:italic>\n                    as a long-chain acyl-CoA synthetase essential for lipid homeostasis, membrane integrity, and oxidative stress resistance reveals a previously unappreciated link between fatty acid metabolism and intramacrophage survival of\n                    <jats:italic>F. tularensis<\/jats:italic>\n                    .\n                  <\/jats:p>\n                <\/jats:sec>","DOI":"10.64898\/2026.05.08.723735","type":"posted-content","created":{"date-parts":[[2026,5,9]],"date-time":"2026-05-09T05:30:24Z","timestamp":1778304624000},"source":"Crossref","is-referenced-by-count":0,"title":["Control of Oxidative Stress and Intracellular Survival in\n                  <i>Francisella tularensis<\/i>\n                  Live Vaccine Strain (LVS) via Acyl-CoA Synthetase"],"prefix":"10.64898","author":[{"given":"Anthony","family":"Centone","sequence":"first","affiliation":[{"name":"Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhuo","family":"Ma","sequence":"additional","affiliation":[{"name":"Department of Life Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Meenakshi","family":"Malik","sequence":"additional","affiliation":[{"name":"Department of Life Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5459-3225","authenticated-orcid":false,"given":"Chandra Shekhar","family":"Bakshi","sequence":"additional","affiliation":[{"name":"Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"54368","reference":[{"key":"2026051208501728000_2026.05.08.723735v1.1","doi-asserted-by":"crossref","first-page":"695","DOI":"10.3390\/biomedicines14030695","article-title":"Tularemia: Historical Perspectives and Current Challenges of a Re-Emerging Zoonosis","volume":"14","year":"2026","journal-title":"Biomedicines"},{"key":"2026051208501728000_2026.05.08.723735v1.2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.micro.60.080805.142126"},{"key":"2026051208501728000_2026.05.08.723735v1.3","doi-asserted-by":"publisher","DOI":"10.3201\/eid0802.010164"},{"key":"2026051208501728000_2026.05.08.723735v1.4","doi-asserted-by":"publisher","DOI":"10.1016\/j.amjms.2018.06.006"},{"key":"2026051208501728000_2026.05.08.723735v1.5","doi-asserted-by":"publisher","DOI":"10.3201\/eid1112.050728"},{"key":"2026051208501728000_2026.05.08.723735v1.6","first-page":"613","article-title":"Identification and Classification of Different Isolates of Francisella tularensis. 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