Agrobacterium tumefaciens estC, Encoding an Enzyme Containing Esterase Activity, Is Regulated by EstR, a Regulator in the MarR Family

• Published in: PloS one Vol. 11; no. 12; p. e0168791
• Main Authors: Rittiroongrad, Surawach, Charoenlap, Nisanart, Giengkam, Suparat, Vattanaviboon, Paiboon, Mongkolsuk, Skorn
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 30-12-2016; Public Library of Science (PLoS)
• Subjects: Agrobacterium tumefaciens; Agrobacterium tumefaciens - genetics; Agrobacterium tumefaciens - metabolism; Amino Acid Sequence; Amino acids; Antibiotics; Bacillus subtilis; Bacteria; Bacterial infections; Bacterial Proteins - genetics; Biology and Life Sciences; Biotechnology; Chemical bonds; Cloning; Cumene; Cumene hydroperoxide; Deactivation; Deoxyribonucleic acid; DNA; Drug resistance; Environmental health; Enzymes; Esterase; Esterases; Esterases - genetics; Gene expression; Gene Expression Regulation, Bacterial - genetics; Gene silencing; Genes; Genetic aspects; Genomes; Hydrogen Peroxide - metabolism; Inactivation; Infections; Laboratories; Menadione; Organic hydroperoxide; Oxidation; Oxidation-Reduction; Oxidative stress; Phylogenetics; Physical Sciences; Physiological aspects; Physiology; Promoter Regions, Genetic; Proteins; Pseudomonas aeruginosa; Repressor Proteins - genetics; Research and Analysis Methods; Sequence Alignment; Staphylococcus aureus; Toxicology; Transcription (Genetics); Transcription Factors - genetics; Xanthomonas campestris
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0168791

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.