title: Agrobacterium tumefaciens estC, Encoding an Enzyme Containing Esterase Activity, Is Regulated by EstR, a Regulator in the MarR Family.
abstract: Analysis of the A. tumefaciens genome revealed estC, which encodes an esterase located next to its transcriptional regulator estR, a regulator of esterase in the MarR family. Inactivation of estC results in a small increase in the resistance to organic hydroperoxides, whereas a high level of expression of estC from an expression vector leads to a reduction in the resistance to organic hydroperoxides and menadione. The estC gene is transcribed divergently from its regulator, estR. Expression analysis showed that only high concentrations of cumene hydroperoxide (CHP, 1 mM) induced expression of both genes in an EstR-dependent manner. The EstR protein acts as a CHP sensor and a transcriptional repressor of both genes. EstR specifically binds to the operator sites OI and OII overlapping the promoter elements of estC and estR. This binding is responsible for transcription repression of both genes. Exposure to organic hydroperoxide results in oxidation of the sensing cysteine (Cys16) residue of EstR, leading to a release of the oxidized repressor from the operator sites, thereby allowing transcription and high levels of expression of both genes. The estC is the first organic hydroperoxide-inducible esterase-encoding gene in alphaproteobacteria.
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.|Department of Biotechnology, and Center of Emerging Bacterial Infection, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Surawach
authors.initials: S
authors.lastname: Rittiroongrad
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.|Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand.
authors.forename: Nisanart
authors.initials: N
authors.lastname: Charoenlap
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.
authors.forename: Suparat
authors.initials: S
authors.lastname: Giengkam
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.|Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand.|Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand.
authors.forename: Paiboon
authors.initials: P
authors.lastname: Vattanaviboon
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.|Department of Biotechnology, and Center of Emerging Bacterial Infection, Faculty of Science, Mahidol University, Bangkok, Thailand.|Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand.|Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand.
authors.forename: Skorn
authors.identifier: http://orcid.org/0000-0001-9698-0004
authors.initials: S
authors.lastname: Mongkolsuk
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D004950:Esterases / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D006861:Hydrogen Peroxide / Q000378:metabolism; D010084:Oxidation-Reduction; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D006861:Hydrogen Peroxide; D004950:Esterases