{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T07:58:10Z","timestamp":1790927890626,"version":"4.1.0"},"reference-count":30,"publisher":"EDP Sciences","license":[{"start":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T00:00:00Z","timestamp":1790899200000},"content-version":"vor","delay-in-days":274,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"DOI":"10.13039\/100020595","name":"National Science and Technology Council","doi-asserted-by":"publisher","award":["NSTC 115-2320-B-039-061-MY3"],"award-info":[{"award-number":["NSTC 115-2320-B-039-061-MY3"]}],"id":[{"id":"10.13039\/100020595","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012544","name":"China Medical University, Taiwan","doi-asserted-by":"publisher","award":["CMU114-S-34"],"award-info":[{"award-number":["CMU114-S-34"]}],"id":[{"id":"10.13039\/501100012544","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100008903","name":"Ministry of Health and Welfare","doi-asserted-by":"publisher","award":["MOHW-YFH-11419"],"award-info":[{"award-number":["MOHW-YFH-11419"]}],"id":[{"id":"10.13039\/100008903","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Parasite"],"accepted":{"date-parts":[[2026,9,21]]},"published-print":{"date-parts":[[2026]]},"abstract":"<jats:p>\n                    <jats:italic>Background<\/jats:italic>\n                    :\n                    <jats:italic>Acanthamoeba castellanii<\/jats:italic>\n                    and\n                    <jats:italic>Klebsiella pneumoniae<\/jats:italic>\n                    are environmental commensals that co-exist in aquatic habitats. Our previous studies demonstrated that\n                    <jats:italic>A. castellanii<\/jats:italic>\n                    genotype T4 (AcT4) induces capsule enlargement and hypermucoviscosity in\n                    <jats:italic>K. pneumoniae<\/jats:italic>\n                    through small excretory\u2013secretory proteins (ESPs; &lt;10\u00a0kDa) that activate the Rcs two-component system, upregulating capsule biosynthesis genes independently of virulence plasmids. However, the molecular identity of these active ESPs remained undefined.\n                    <jats:italic>Results<\/jats:italic>\n                    : To identify candidate proteins, we performed label-free quantitative proteomics (LC-MS\/MS) on conditioned medium from AcT4 co-cultured with\n                    <jats:italic>K. pneumoniae<\/jats:italic>\n                    (Ac\/Kp)\n                    <jats:italic>versus<\/jats:italic>\n                    AcT4 alone (Ac only;\n                    <jats:italic>n<\/jats:italic>\n                    \u00a0=\u00a03 per group). A total of 391\n                    <jats:italic>A. castellanii<\/jats:italic>\n                    proteins were identified; seven showed significantly increased extracellular abundance in Ac\/Kp medium (log\n                    <jats:sub>2<\/jats:sub>\n                    \u2009ratio\u00a0\u2265\u00a01,\n                    <jats:italic>p<\/jats:italic>\n                    \u00a0&lt;\u00a00.05), and 98 showed decreased abundance. Functional enrichment analysis revealed that increased-abundance proteins were enriched in transport, signaling\/regulation, redox activity, ion\/metal binding, and chaperone\/stress response categories. Among these, a C-type lysozyme\/\u03b1-lactalbumin superfamily protein (UniProt L8GZI4; 14.7\u00a0kDa; log\n                    <jats:sub>2<\/jats:sub>\n                    \u2009ratio\u00a0=\u00a05.19) was identified as a priority candidate, as lysozyme-mediated peptidoglycan hydrolysis generates muropeptides\u2014known activators of the Rcs phosphorelay.\n                    <jats:italic>Conclusions<\/jats:italic>\n                    : This comparative secretome analysis provides the first proteomic catalogue of AcT4 extracellular proteins during co-culture with\n                    <jats:italic>K. pneumoniae<\/jats:italic>\n                    and identifies C-type lysozyme as a biologically plausible candidate mediating Rcs-dependent capsule induction. These findings lay the groundwork for future validation of AcT4-derived ESPs in protozoa\u2013bacteria interactions and their potential role in the environmental emergence of hypervirulent\n                    <jats:italic>K. pneumoniae<\/jats:italic>\n                    .\n                  <\/jats:p>","DOI":"10.1051\/parasite\/2026057","type":"journal-article","created":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T07:51:52Z","timestamp":1790927512000},"page":"57","source":"Crossref","is-referenced-by-count":0,"title":["Proteomic identification of\n                    <i>Acanthamoeba castellanii<\/i>\n                    excretory\u2013secretory proteins associated with\n                    <i>Klebsiella pneumoniae<\/i>\n                    capsule enlargement: a candidate role for C-type lysozyme"],"prefix":"10.1051","volume":"33","author":[{"given":"Chun-Hsien","family":"Chen","sequence":"first","affiliation":[{"name":"Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University","place":["Taiwan"]},{"name":"Department of Parasitology, College of Medicine, Chang Gung University","place":["Taiwan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jian-Ming","family":"Huang","sequence":"additional","affiliation":[{"name":"School of Medicine, National Tsing Hua University","place":["Taiwan"]},{"name":"Institute of Molecular and Cellular Biology, National Tsing Hua University","place":["Taiwan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wei-Chen","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Parasitology, College of Medicine, National Cheng Kung University","place":["Taiwan"]},{"name":"Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University","place":["Taiwan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chih-Ming","family":"Tsai","sequence":"additional","affiliation":[{"name":"Department of Parasitology, College of Medicine, National Cheng Kung University","place":["Taiwan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hsin-Yu","family":"Hsieh","sequence":"additional","affiliation":[{"name":"Department of Nursing, Feng Yuan Hospital, Ministry of Health and Welfare","place":["Taiwan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2981-9429","authenticated-orcid":false,"given":"Yu-Jen","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Parasitology, School of Medicine, China Medical University","place":["Taiwan"]},{"name":"Graduate Institute of Biomedical Sciences, China Medical University","place":["Taiwan"]},{"name":"Departments of Laboratory Medicine and Internal Medicine, China Medical University 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