Thanittra DokpikulPaweena ChaoprasidKritsakorn SaninjukSirin SirirakphaisarnJaruwan JohnrodSumontha NookabkaewRojana SukchawalitSkorn MongkolsukEnvironmental ToxicologyChulabhorn Research InstituteMahidol UniversityChulabhorn Graduate InstituteThailand Ministry of Education2018-12-112019-03-142018-12-112019-03-142016-01-01Applied and Environmental Microbiology. Vol.82, No.15 (2016), 4732-474210985336009922402-s2.0-84979944301https://repository.li.mahidol.ac.th/handle/20.500.14594/42793© 2016, American Society for Microbiology. The Agrobacterium tumefaciens C58 genome harbors an operon containing the dmeR (Atu0890) and dmeF (Atu0891) genes, which encode a transcriptional regulatory protein belonging to the RcnR/CsoR family and a metal efflux protein belonging to the cation diffusion facilitator (CDF) family, respectively. The dmeRF operon is specifically induced by cobalt and nickel, with cobalt being the more potent inducer. Promoter-lacZ transcriptional fusion, an electrophoretic mobility shift assay, and DNase I footprinting assays revealed that DmeR represses dmeRF transcription through direct binding to the promoter region upstream of dmeR. A strain lacking dmeF showed increased accumulation of intracellular cobalt and nickel and exhibited hypersensitivity to these metals; however, this strain displayed full virulence, comparable to that of the wild-type strain, when infecting a Nicotiana benthamiana plant model under the tested conditions. Cobalt, but not nickel, increased the expression of many iron-responsive genes and reduced the induction of the SoxR-regulated gene sodBII. Furthermore, control of iron homeostasis via RirA is important for the ability of A. tumefaciens to cope with cobalt and nickel toxicity.Mahidol UniversityAgricultural and Biological SciencesBiochemistry, Genetics and Molecular BiologyEnvironmental ScienceImmunology and MicrobiologyArticleSCOPUS10.1128/AEM.01262-16