{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T05:41:03Z","timestamp":1785908463833,"version":"3.56.0"},"reference-count":47,"publisher":"American Society for Microbiology","issue":"3","license":[{"start":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T00:00:00Z","timestamp":1774915200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T00:00:00Z","timestamp":1774915200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"DOI":"10.13039\/501100008111","name":"Hainan Provincial Department of Science and Technology","doi-asserted-by":"publisher","award":["825RC764"],"award-info":[{"award-number":["825RC764"]}],"id":[{"id":"10.13039\/501100008111","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100008111","name":"Hainan Provincial Department of Science and Technology","doi-asserted-by":"publisher","award":["825QN334"],"award-info":[{"award-number":["825QN334"]}],"id":[{"id":"10.13039\/501100008111","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["U24A20747"],"award-info":[{"award-number":["U24A20747"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100007935","name":"Hainan Medical University","doi-asserted-by":"publisher","award":["XSTS2025159"],"award-info":[{"award-number":["XSTS2025159"]}],"id":[{"id":"10.13039\/501100007935","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["mSphere"],"published-print":{"date-parts":[[2026,3,31]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      <jats:italic toggle=\"yes\">Burkholderia pseudomallei<\/jats:italic>\n                      , which causes melioidosis, is an adaptable pathogen that survives in diverse environments. Two-component systems (TCSs) play pivotal roles in bacterial signal transduction and adaptation, yet the functions of most TCSs in\n                      <jats:italic toggle=\"yes\">B. pseudomallei<\/jats:italic>\n                      remain poorly characterized. Here, we identified and functionally characterized a previously unstudied TCS, IrlS2-IrlR2, which shares partial homology with the IrlS-IrlR system but exhibits distinct regulatory roles. Knockout of\n                      <jats:italic toggle=\"yes\">irlR2<\/jats:italic>\n                      (\u0394\n                      <jats:italic toggle=\"yes\">irlR2<\/jats:italic>\n                      ) did not affect growth in nutrient-rich medium but led to enhanced biofilm formation, reduced motility, decreased siderophore production, and increased sensitivity to oxidative stress, all of which were restored in the complemented strain. The mutant also exhibited growth retardation under subinhibitory cobalt concentrations, despite unchanged MICs. In infection assays, \u0394\n                      <jats:italic toggle=\"yes\">irlR2<\/jats:italic>\n                      displayed impaired adhesion and cytotoxicity toward A549 cells and attenuated virulence in\n                      <jats:italic toggle=\"yes\">Galleria mellonella<\/jats:italic>\n                      , with a higher median lethal dose than the wild type. Transcriptomic analysis revealed\n                      <jats:italic toggle=\"yes\">hcp2<\/jats:italic>\n                      within the type VI secretion system 2 (T6SS-2) cluster, and multiple T3SS-3 genes were strongly downregulated, consistent with reduced intracellular survival, whereas T3SS-1 and T3SS-2 were upregulated, suggesting a dysregulated secretion system balance. Adhesion-related (\n                      <jats:italic toggle=\"yes\">fimA<\/jats:italic>\n                      ) and iron transport (\n                      <jats:italic toggle=\"yes\">fhuBCDF<\/jats:italic>\n                      ) genes were repressed, while oxidative stress-associated (\n                      <jats:italic toggle=\"yes\">cydABX<\/jats:italic>\n                      ) and nitrate reductase (\n                      <jats:italic toggle=\"yes\">narIJHGK-nasA<\/jats:italic>\n                      ) operons were induced, indicating altered regulation of iron homeostasis, redox balance, and nitrogen metabolism, which may reflect adaptive responses to environmental stress. Collectively, these results demonstrate that the IrlS2-IrlR2 system functions as a global regulator, integrating biofilm formation, stress adaptation, and virulence regulation, highlighting its role in the environmental resilience and pathogenic potential of\n                      <jats:italic toggle=\"yes\">B. pseudomallei<\/jats:italic>\n                      .\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>IMPORTANCE<\/jats:title>\n                    <jats:p>\n                      <jats:italic toggle=\"yes\">Burkholderia pseudomallei<\/jats:italic>\n                      , which causes melioidosis, poses a serious threat to human and animal health in tropical and subtropical regions worldwide. Classified as a tier 1 biothreat agent by the U.S. CDC and a category II pathogen in China,\n                      <jats:italic toggle=\"yes\">B. pseudomallei<\/jats:italic>\n                      causes severe pneumonia and septicemia with case-fatality rates approaching 50%. Despite its medical and epidemiological significance, the regulatory mechanisms controlling its virulence and environmental persistence remain poorly understood. This study identifies IrlS2-IrlR2 as a previously uncharacterized two-component system (TCS) that acts as a global regulator integrating biofilm formation, stress adaptation, and virulence. Functional and transcriptomic analyses reveal that IrlS2-IrlR2 modulates secretion systems, iron homeostasis, and redox balance. These findings deepen our understanding of\n                      <jats:italic toggle=\"yes\">B. pseudomallei<\/jats:italic>\n                      pathogenesis and highlight the role of TCS-mediated regulatory networks.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1128\/msphere.00744-25","type":"journal-article","created":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T14:00:11Z","timestamp":1772114411000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":1,"title":["The IrlS2-IrlR2 two-component system is a global regulator of biofilm formation, stress adaptation, and virulence in\n                    <i>Burkholderia pseudomallei<\/i>"],"prefix":"10.1128","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0009-0003-2873-7602","authenticated-orcid":false,"given":"Fang","family":"Chen","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/004eeze55","id-type":"ROR","asserted-by":"publisher"}],"name":"NHC Key Laboratory of Tropical Disease Control, School of Life Sciences and Medical Technology, Hainan Medical University","place":["Haikou, China"]},{"name":"Department of Infectious and Tropical Diseases, The Second Affiliated Hospital of Hainan Medical University","place":["Haikou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jian","family":"Luo","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/004eeze55","id-type":"ROR","asserted-by":"publisher"}],"name":"NHC Key Laboratory of Tropical Disease Control, School of Life Sciences and Medical Technology, Hainan Medical University","place":["Haikou, 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