{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T13:23:36Z","timestamp":1788269016930,"version":"build-2803163510"},"reference-count":49,"publisher":"American Society for Microbiology","issue":"9","license":[{"start":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T00:00:00Z","timestamp":1788220800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T00:00:00Z","timestamp":1788220800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["Microbiol Spectr"],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      The MgtC virulence factor is important during the intramacrophage stage in both classical intracellular pathogens, such as\n                      <jats:italic toggle=\"yes\">Salmonella<\/jats:italic>\n                      Typhimurium, and in extracellular bacteria that transiently encounter intracellular environments during infection, such as\n                      <jats:italic toggle=\"yes\">Pseudomonas aeruginosa<\/jats:italic>\n                      . In these different pathogens,\n                      <jats:italic toggle=\"yes\">mgtC<\/jats:italic>\n                      expression is induced\n                      <jats:italic toggle=\"yes\">in vitro<\/jats:italic>\n                      by magnesium ion depletion, a condition reported to mimic the macrophage environment. Here, we developed an unstable GFP reporter system to monitor in real time the transcriptional activation of the\n                      <jats:italic toggle=\"yes\">P. aeruginosa mgtC<\/jats:italic>\n                      promoter. After\n                      <jats:italic toggle=\"yes\">in vitro<\/jats:italic>\n                      validation in magnesium-defined media, this reporter system allowed visualization of the\n                      <jats:italic toggle=\"yes\">mgtC<\/jats:italic>\n                      promoter induction in a subset of bacteria when\n                      <jats:italic toggle=\"yes\">P. aeruginosa<\/jats:italic>\n                      localized inside cultured macrophages. In addition, although rare under our experimental conditions,\n                      <jats:italic toggle=\"yes\">in vivo<\/jats:italic>\n                      activation of the\n                      <jats:italic toggle=\"yes\">mgtC<\/jats:italic>\n                      promoter was observed for the first time within macrophages of live, infected zebrafish larvae, a cutting-edge vertebrate model for real-time imaging. While MgtC regulation in\n                      <jats:italic toggle=\"yes\">Salmonella<\/jats:italic>\n                      is mediated by the magnesium-responsive PhoPQ two-component system, its regulation in\n                      <jats:italic toggle=\"yes\">P. aeruginosa<\/jats:italic>\n                      remained unknown. The use of mutant strains for two-component regulatory systems revealed that the PhoP regulator, but not by its cognate sensor PhoQ, was required to activate\n                      <jats:italic toggle=\"yes\">P. aeruginosa<\/jats:italic>\n                      MgtC expression\n                      <jats:italic toggle=\"yes\">in vitro<\/jats:italic>\n                      . Unexpectedly, CbrAB, a two-component system specific to\n                      <jats:italic toggle=\"yes\">Pseudomonas<\/jats:italic>\n                      species, was also involved in\n                      <jats:italic toggle=\"yes\">P. aeruginosa<\/jats:italic>\n                      MgtC regulation. Both PhoP and CbrB regulatory proteins were found to directly bind the\n                      <jats:italic toggle=\"yes\">mgtC<\/jats:italic>\n                      promoter, supporting a dual transcriptional control. These findings reveal substantial differences in\n                      <jats:italic toggle=\"yes\">mgtC<\/jats:italic>\n                      gene regulation in different bacterial pathogens, reflecting distinct strategies to drive appropriate expression of a shared virulence factor involved in macrophage adaptation.\n                    <\/jats:p>\n                    <jats:sec>\n                      <jats:title>IMPORTANCE<\/jats:title>\n                      <jats:p>\n                        The adaptation of bacterial pathogens to the host intracellular microenvironment requires tight and rapid regulation of specific genes, and investigating the\n                        <jats:italic toggle=\"yes\">in vivo<\/jats:italic>\n                        transcriptional dynamics of such genes is a major challenge. Here, we focused on the expression of\n                        <jats:italic toggle=\"yes\">mgtC<\/jats:italic>\n                        , a gene important for adaptation to the intramacrophage environment in classical intracellular pathogens, such as\n                        <jats:italic toggle=\"yes\">Salmonella<\/jats:italic>\n                        Typhimurium, and bacteria with a transient intracellular lifestyle, such as\n                        <jats:italic toggle=\"yes\">Pseudomonas aeruginosa<\/jats:italic>\n                        . An unstable GFP reporter system was designed to monitor the transcriptional dynamics of\n                        <jats:italic toggle=\"yes\">P. aeruginosa mgtC<\/jats:italic>\n                        . The use of this reporter system in a state-of-the-art vertebrate model for live imaging, the zebrafish embryo, allowed\n                        <jats:italic toggle=\"yes\">in vivo<\/jats:italic>\n                        tracking of\n                        <jats:italic toggle=\"yes\">P. aeruginosa mgtC<\/jats:italic>\n                        promoter activation inside macrophages in a living host. Furthermore, the expression of\n                        <jats:italic toggle=\"yes\">P. aeruginosa mgtC<\/jats:italic>\n                        was found to be regulated through a mechanism distinct from that of\n                        <jats:italic toggle=\"yes\">Salmonella<\/jats:italic>\n                        MgtC, since it involves the PhoP regulatory protein, but not the PhoQ sensor, and the\n                        <jats:italic toggle=\"yes\">Pseudomonas<\/jats:italic>\n                        -specific CbrAB two-component system, reflecting diverse, finely tuned strategies to control a virulence factor shared by several major human pathogens.\n                      <\/jats:p>\n                    <\/jats:sec>\n                  <\/jats:sec>","DOI":"10.1128\/spectrum.00064-26","type":"journal-article","created":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T13:00:40Z","timestamp":1785934840000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["<i>Pseudomonas aeruginosa mgtC<\/i>\n                    gene is under the control of PhoP and CbrAB regulators, and its expression can be visualized in macrophages"],"prefix":"10.1128","volume":"14","author":[{"given":"Anne","family":"Bonhoure","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/051escj72","id-type":"ROR","asserted-by":"publisher"}],"name":"Laboratory of Pathogens and Host Immunity (LPHI), Universit\u00e9 de Montpellier, CNRS","place":["Montpellier, France"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pauline","family":"Nogaret","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/051escj72","id-type":"ROR","asserted-by":"publisher"}],"name":"Laboratory of Pathogens and Host Immunity (LPHI), Universit\u00e9 de Montpellier, CNRS","place":["Montpellier, France"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Val\u00e9rie","family":"Perez","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/051escj72","id-type":"ROR","asserted-by":"publisher"}],"name":"Laboratory of Pathogens and Host Immunity (LPHI), Universit\u00e9 de Montpellier, CNRS","place":["Montpellier, France"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Flore","family":"Nilly","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/051escj72","id-type":"ROR","asserted-by":"publisher"}],"name":"Laboratory of Pathogens and Host Immunity (LPHI), Universit\u00e9 de Montpellier, CNRS","place":["Montpellier, France"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sylvaine","family":"Huc-Brandt","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/051escj72","id-type":"ROR","asserted-by":"publisher"}],"name":"Laboratory of Pathogens and Host Immunity (LPHI), Universit\u00e9 de Montpellier, CNRS","place":["Montpellier, France"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Malika","family":"Moussouni","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/051escj72","id-type":"ROR","asserted-by":"publisher"}],"name":"Laboratory of Pathogens and Host Immunity (LPHI), Universit\u00e9 de Montpellier, CNRS","place":["Montpellier, France"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5989-8503","authenticated-orcid":true,"given":"Robert E. 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