{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T06:09:05Z","timestamp":1789711745893,"version":"4.0.1"},"reference-count":30,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T00:00:00Z","timestamp":1789689600000},"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. Microbiol."],"abstract":"<jats:p>\n                    <jats:italic>Acinetobacter baumannii<\/jats:italic>\n                    is a multidrug-resistant pathogen capable of metabolizing host-derived acyl-L-carnitines, which contributes to its virulence. During\n                    <jats:italic>A. baumannii<\/jats:italic>\n                    growth on acetyl-L-carnitine, L-carnitine was initially released into the growth medium suggesting that acetate is metabolized first. The subsequent uptake of L-carnitine at the end of the exponential phase then facilitates the catabolism of L-carnitine. Involvement of the betaine\/choline\/carnitine transporter (BCCT) in the uptake of short- and medium-chain acyl-L-carnitines was confirmed through growth experiments using the \u0394\n                    <jats:italic>bcct<\/jats:italic>\n                    mutant strain. An uncharacterized hydrolase (HMPREF0010_01348) encoded by the L-carnitine degradation gene operon (HMPREF0010_01345 \u2013 HMPREF0010_01351) was biochemically identified as a short- and medium-chain acyl-L-carnitine hydrolase (ACH). Its cellular localization in the cytoplasm was demonstrated. The purified ACH exhibited no enzymatic activity toward long-chain acyl-L-carnitines. However, growth experiments revealed that both the wild type and the \u0394\n                    <jats:italic>ach<\/jats:italic>\n                    mutant were able to grow clearly on these substrates, providing evidence for the involvement of an additional, as-yet-uncharacterized enzyme. The cell culture supernatant was used for the chromatographic enrichment of a protein fraction showing robust enzyme activity for the hydrolysis of long-chain acyl-L-carnitines. Proteomic analysis of a partially purified hydrolase fraction and of the\n                    <jats:italic>A. baumannii<\/jats:italic>\n                    secretome revealed the gene product of open reading frame HMPREF0010_02333 as a hydrolase candidate. The respective protein was recombinantly overproduced and purified and its ability to cleave various long-chain acyl-L-carnitines was demonstrated. Based on the substrate specificity of the characterized ACH from the cytosol and the acyl-L-carnitine hydrolase present in the culture supernatant (ACHS), a metabolic model for the versatile utilization of small- medium- and long-chain acyl-L-carnitines by\n                    <jats:italic>A. baumannii<\/jats:italic>\n                    was proposed.\n                  <\/jats:p>","DOI":"10.3389\/fmicb.2026.1964901","type":"journal-article","created":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T05:38:12Z","timestamp":1789709892000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Metabolic versatility of Acinetobacter baumannii: distinct pathways for the utilization of short-, medium- and long-chain acyl-L-carnitines"],"prefix":"10.3389","volume":"17","author":[{"given":"Paula","family":"Schwerdhelm","sequence":"first","affiliation":[{"name":"Institute of Microbiology, Technische Universit\u00e4t Braunschweig","place":["Braunschweig, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kateryna","family":"Podrez","sequence":"additional","affiliation":[{"name":"Institute of Microbiology, Technische Universit\u00e4t Braunschweig","place":["Braunschweig, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Julian","family":"Kaltenh\u00e4user","sequence":"additional","affiliation":[{"name":"Institute of Microbiology, Technische Universit\u00e4t Braunschweig","place":["Braunschweig, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simon","family":"Sivov","sequence":"additional","affiliation":[{"name":"Institute of Microbiology, Technische Universit\u00e4t Braunschweig","place":["Braunschweig, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Beate","family":"Averhoff","sequence":"additional","affiliation":[{"name":"Institute of Molecular Biosciences, Goethe-Universit\u00e4t Frankfurt","place":["Frankfurt, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dominik","family":"K\u00f6rner","sequence":"additional","affiliation":[{"name":"Department of Cellular Proteome Research, Helmholtz Centre for Infection Research","place":["Braunschweig, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lothar","family":"J\u00e4nsch","sequence":"additional","affiliation":[{"name":"Department of Cellular Proteome Research, Helmholtz Centre for Infection Research","place":["Braunschweig, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dieter","family":"Jahn","sequence":"additional","affiliation":[{"name":"Institute of Microbiology, Technische Universit\u00e4t Braunschweig","place":["Braunschweig, Germany"]},{"name":"Braunschweig Centre of Integrated Systems Biology","place":["Braunschweig, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J\u00fcrgen","family":"Moser","sequence":"additional","affiliation":[{"name":"Institute of Microbiology, Technische Universit\u00e4t Braunschweig","place":["Braunschweig, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,18]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"577856","DOI":"10.3389\/fphys.2020.577856","article-title":"Long-chain Acylcarnitines and cardiac excitation-contraction coupling: links to arrhythmias","volume":"11","author":"Aitken-Buck","year":"2020","journal-title":"Front. 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