{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,25]],"date-time":"2025-10-25T12:39:49Z","timestamp":1761395989412,"version":"build-2065373602"},"reference-count":40,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,3,24]],"date-time":"2021-03-24T00:00:00Z","timestamp":1616544000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Research Foundation of Korea","award":["NRF-2018R1D1A1B07048097"],"award-info":[{"award-number":["NRF-2018R1D1A1B07048097"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pathogens"],"abstract":"<jats:p>Naegleria fowleri is a free-living amoeba that is ubiquitous in diverse natural environments. It causes a fatal brain infection in humans known as primary amoebic meningoencephalitis. Despite the medical importance of the parasitic disease, there is a great lack of knowledge about the biology and pathogenicity of N. fowleri. In this study, we identified and characterized a novel cysteine protease inhibitor of N. fowleri (NfCPI). NfCPI is a typical cysteine protease inhibitor belonging to the cystatin family with a Gln-Val-Val-Ala-Gly (QVVAG) motif, a characteristic motif conserved in the cystatin family of proteins. Bacterially expressed recombinant NfCPI has a dimeric structure and exhibits inhibitory activity against several cysteine proteases including cathespin Bs of N. fowleri at a broad range of pH values. Expression profiles of nfcpi revealed that the gene was highly expressed during encystation and cyst of the amoeba. Western blot and immunofluorescence assays also support its high level of expression in cysts. These findings collectively suggest that NfCPI may play a critical role in encystation or cyst formation of N. fowleri by regulating cysteine proteases that may mediate encystation or mature cyst formation of the amoeba. More comprehensive studies to investigate the roles of NfCPI in encystation and its target proteases are necessary to elucidate the regulatory mechanism and the biological significance of NfCPI.<\/jats:p>","DOI":"10.3390\/pathogens10040388","type":"journal-article","created":{"date-parts":[[2021,3,24]],"date-time":"2021-03-24T21:36:51Z","timestamp":1616621811000},"page":"388","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["A Novel Cysteine Protease Inhibitor of Naegleria fowleri That Is Specifically Expressed during Encystation and at Mature Cysts"],"prefix":"10.3390","volume":"10","author":[{"given":"H\u01b0\u01a1ng Giang","family":"L\u00ea","sequence":"first","affiliation":[{"name":"Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea"},{"name":"Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"A-Jeong","family":"Ham","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Ajou University College of Medicine, Suwon 16499, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jung-Mi","family":"Kang","sequence":"additional","affiliation":[{"name":"Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea"},{"name":"Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tu\u1ea5n C\u01b0\u1eddng","family":"V\u00f5","sequence":"additional","affiliation":[{"name":"Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea"},{"name":"Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Haung","family":"Naw","sequence":"additional","affiliation":[{"name":"Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea"},{"name":"Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hae-Jin","family":"Sohn","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Ajou University College of Medicine, Suwon 16499, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ho-Joon","family":"Shin","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Ajou University College of Medicine, Suwon 16499, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6734-1673","authenticated-orcid":false,"given":"Byoung-Kuk","family":"Na","sequence":"additional","affiliation":[{"name":"Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea"},{"name":"Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,3,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"968","DOI":"10.1017\/S0950268809991014","article-title":"The epidemiology of primary amoebic meningoencephalitis in the USA, 1962\u20132008","volume":"138","author":"Yoder","year":"2010","journal-title":"Epidemiol. 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