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The 228bp upstream non-coding region of haloacids transporter gene dehp2 has regulated promoter activity

Su, Xianbin, Li, Ruihong, Tsang, Jimmy S.H.
Gene 2016 v.593 no.2 pp. 322-329
Burkholderia, biodegradation, dehalogenation, gel electrophoresis, hybridization, operon, pollutants, quantitative polymerase chain reaction, sequence homology
Biodegradation is an effective way to remove environmental pollutants haloacids, and haloacids uptake is an important step besides cytoplasmic dehalogenation. Previous study has identified a robust haloacids transport system in Burkholderia caribensis MBA4 with two homologous genes deh4p and dehp2 as major players. Both genes are inducible by monochloroacetate (MCA), and dehp2 is conserved among the Burkholderia genus with a two component system upstream. Here we show that dehp2 is not in the same operon with the upstream two component system, and fusion with lacZ confirmed the presence of MCA-inducible promoter activity in the 228bp upstream non-coding region of dehp2. Serial deletion confirmed 112bp upstream is enough for basic promoter activity, but sequence further upstream is useful for enhanced promoter activity. Electrophoretic mobility shift assay of the 228bp region showed a retardation complex with stronger hybridization in the induced condition, suggesting a positive regulation pattern. Regulator(s) binding region was found to lie between −228 to −113bp of dehp2. Quantitative real-time PCR showed that the expressions of dehp2 orthologs in three other Burkholderia species were also MCA-inducible, similar as dehp2. The 5′ non-coding regions of these dehp2 orthologs have high sequence similarity with dehp2 promoter, and 100bp upstream of dehp2 orthologs is especially conserved. Our study identified a promoter of haloacids transporter gene that is conserved in the Burkholderia genus, which will benefit future exploitation of them for effective biodegradation of haloacids.