{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T17:06:22Z","timestamp":1788541582851,"version":"build-2803163510"},"reference-count":51,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2025,10,31]],"date-time":"2025-10-31T00:00:00Z","timestamp":1761868800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Science and Technology Council","award":["MOST111-2635B320-001-MY2"],"award-info":[{"award-number":["MOST111-2635B320-001-MY2"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Two-component systems (TCSs) in bacteria are often involved in the global regulation of various physiological activities and behaviours. This study investigated the GacSA TCS and DJ41_1407 transcriptional sensor adjacent to GacA in Acinetobacter baumannii ATCC 19606. The relationship between GacS, GacA, and DJ41_1407 and their functions and signal transduction mechanisms are described. A. baumannii ATCC 19606 mutants, \u2206gacS, \u2206gacA, and \u2206DJ41_1407, were generated using markerless mutation and cultured in LB medium, then collected for RNA sequencing. It was found that GacS, GacA, and DJ41_1407 regulate a series of genes involved in carbon metabolism. Quantitative reverse transcription PCR (qRT-PCR) results showed that DJ41_1407 and GacA may regulate the expression of adh4, ipdC, iacH, and paa. Phos-tag\u2122 results revealed that GacS plays a more significant role in GacA phosphorylation. GacA regulated colony size and growth conditions in rich medium. Compared to the wild-type strain, the \u2206gacA and \u2206gacSA mutants exhibited smaller colony sizes, and mutation of the gacS, gacA, and DJ41_1407 genes also reduced bacterial virulence as determined by the Galleria mellonella infection assay. GacA also plays a crucial role in modulating antibiotic resistance, and the \u2206gacA\u2206DJ41_1407 mutant demonstrated greater susceptibility to antibiotics. These results highlight the multiple functions regulated by the GacSA global TCS in A. baumannii ATCC 19606.<\/jats:p>","DOI":"10.3390\/ijms262110620","type":"journal-article","created":{"date-parts":[[2025,11,3]],"date-time":"2025-11-03T13:15:14Z","timestamp":1762175714000},"page":"10620","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Roles of GacSA and DJ41_1407 in Acinetobacter baumannii ATCC 19606"],"prefix":"10.3390","volume":"26","author":[{"given":"Yee-Huan","family":"Toh","sequence":"first","affiliation":[{"name":"Master Program in Biomedical Sciences, School of Medicine, Tzu Chi University, Hualien 970374, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Meng-Yun","family":"Wen","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Immunology, School of Medicine, Tzu Chi University, Hualien 970374, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5218-9322","authenticated-orcid":false,"given":"Guang-Huey","family":"Lin","sequence":"additional","affiliation":[{"name":"Master Program in Biomedical Sciences, School of Medicine, Tzu Chi University, Hualien 970374, Taiwan"},{"name":"Department of Microbiology and Immunology, School of Medicine, Tzu Chi University, Hualien 970374, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"583","DOI":"10.1590\/0037-8682-0161-2014","article-title":"Ecological competition and the incidence of Acinetobacter baumannii bloodstream infections in a teaching hospital in Southeastern Brazil","volume":"47","author":"Lastoria","year":"2014","journal-title":"Rev. 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