{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:14:46Z","timestamp":1760058886903,"version":"build-2065373602"},"reference-count":52,"publisher":"Public Library of Science (PLoS)","issue":"10","license":[{"start":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T00:00:00Z","timestamp":1759968000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/"}],"funder":[{"DOI":"10.13039\/100006492","name":"Division of Intramural Research, National Institute of Allergy and Infectious Diseases","doi-asserted-by":"publisher","award":["1R01AI166537-03"],"award-info":[{"award-number":["1R01AI166537-03"]}],"id":[{"id":"10.13039\/100006492","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004442","name":"National Science Centre","doi-asserted-by":"crossref","award":["2021\/42\/A\/NZ1\/00214"],"award-info":[{"award-number":["2021\/42\/A\/NZ1\/00214"]}],"id":[{"id":"10.13039\/501100004442","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["www.plospathogens.org"],"crossmark-restriction":false},"short-container-title":["PLoS Pathog"],"abstract":"<jats:p>The increasing worldwide trend of antibiotic-resistant <jats:italic>Neisseria gonorrhoeae<\/jats:italic> strains highlights the urgent need for new therapeutic strategies against this sexually transmitted pathogen, including a gonococcal vaccine. We previously designed a bioinformatics-based candidate selection pipeline (CASS) and identified potential novel gonococcal vaccine targets among hypothetical proteins expressed during natural human infection. One of these candidates, NGO1701, is a predicted periplasmic four-helix bundle protein with amino acid sequence homology to the copper storage protein 1 (Csp1) from <jats:italic>Methylosinus trichosporium<\/jats:italic> OB3b. In this study, we confirmed that purified NGO1701 binds 15 Cu(I) ions per monomer <jats:italic>in vitro<\/jats:italic>, supporting its function as Csp in <jats:italic>N. gonorrhoeae<\/jats:italic>. Using a <jats:italic>ngo1701<\/jats:italic> deletion mutant generated in <jats:italic>N. gonorrhoeae<\/jats:italic> F62, we investigated its role in bacteria physiology. We showed that ablation of Csp was not limiting for bacterial growth and fitness <jats:italic>in vitro<\/jats:italic>, but the \u0394<jats:italic>csp<\/jats:italic> strain became significantly more susceptible to copper mediated toxicity. This phenotype was rescued by <jats:italic>csp<\/jats:italic> gene complementation, indicating a role in protection against copper toxicity. Our results indicate that Csp participates in periplasmic copper homeostasis in <jats:italic>N. gonorrhoeae,<\/jats:italic> buffering excess copper to reduce toxicity and playing a putative role in copper delivery to important copper-enzymes. Csp does not appear to be involved in bacterial host cell interaction and activation <jats:italic>in vitro<\/jats:italic>, since no difference in the ability of <jats:italic>N. gonorrhoeae<\/jats:italic> to adhere\/invade epithelial cells or induce IL-8 secretion was reported among wild type, <jats:italic>csp<\/jats:italic> deletion mutant and complemented strains. Furthermore, sera from mice immunized with NGO1701 failed to recognize \u0394<jats:italic>csp<\/jats:italic> by dot blot and ELISA, and the sera\u2019s ability to kill <jats:italic>N. gonorrhoeae<\/jats:italic> was abrogated against \u0394<jats:italic>csp<\/jats:italic>. However, both functions were restored after gene complementation, supporting the relevance of Csp as a potential vaccine target. Allelic analysis of Neisseria species revealed that this gene is absent in <jats:italic>N. meningitidis<\/jats:italic>, thus making it a gonococcal-specific target.<\/jats:p>","DOI":"10.1371\/journal.ppat.1013559","type":"journal-article","created":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:26:06Z","timestamp":1760030766000},"page":"e1013559","update-policy":"https:\/\/doi.org\/10.1371\/journal.ppat.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["The gonococcal vaccine candidate antigen NGO1701 is a N. gonorrhoeae periplasmic copper storage protein"],"prefix":"10.1371","volume":"21","author":[{"given":"Shea K.","family":"Roe","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rafa\u0142","family":"Mazgaj","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tianmou","family":"Zhu","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mariam","family":"Esmaeeli","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lisa A.","family":"Lewis","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Caroline","family":"Genco","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kevin J.","family":"Waldron","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3106-0711","authenticated-orcid":true,"given":"Paola","family":"Massari","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2025,10,9]]},"reference":[{"key":"ppat.1013559.ref001","unstructured":"CDC. 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