Bacterial Transcriptional Regulators for Degradation Pathways of Aromatic Compounds

Abstract

Human activities have resulted in the release and introduction into the environment of a plethora of aromatic chemicals. The interest in discovering how bacteria are dealing with hazardous environmental pollutants has driven a large research community and has resulted in important biochemical, genetic, and physiological knowledge about the degradation capacities of microorganisms and their application in bioremediation, green chemistry, or production of pharmacy synthons. In addition, regulation of catabolic pathway expression has attracted the interest of numerous different groups, and several catabolic pathway regulators have been exemplary for understanding transcription control mechanisms. More recently, information about regulatory systems has been used to construct whole-cell living bioreporters that are used to measure the quality of the aqueous, soil, and air environment. The topic of biodegradation is relatively coherent, and this review presents a coherent overview of the regulatory systems involved in the transcriptional control of catabolic pathways. This review summarizes the different regulatory systems involved in biodegradation pathways of aromatic compounds linking them to other known protein families. Specific attention has been paid to describing the genetic organization of the regulatory genes, promoters, and target operon(s) and to discussing present knowledge about signaling molecules, DNA binding properties, and operator characteristics, and evidence from regulatory mutants. For each regulator family, this information is combined with recently obtained protein structural information to arrive at a possible mechanism of transcription activation. This demonstrates the diversity of control mechanisms existing in catabolic pathways

Sustainable syntrophic growth of Dehalococcoides ethenogenes strain 195 with Desulfovibrio vulgaris Hildenborough and Methanobacterium congolense: global transcriptomic and proteomic analyses

“…Genes significantly up-regulated in the co-culture included those predicted to encode glutaredoxin family protein reductase (DET0198, fourfold), ferredoxin-thioredoxin reductase (DET0199, threefold), superoxide dismutase (DET0956, fourfold), antioxidant alkyl hydroperoxide reductase (AhpC; DET1581, threefold) and the a-crystallin heat-shock family protein (DET0954, Table S4). MarR mediates response to multiple environmental stresses (Tropel and van der Meer, 2004) and the TetR family has been linked with cell density-sensing regulatory cascades (Ramos et al, 2005). Interestingly, the observed stress response was not accompanied by a reduction in apparent growth rate of DE195 grown in the co-culture.…”

Genome sequence of the chlorinated compound–respiring bacterium Dehalococcoides species strain CBDB1

“…This gene organization is identical with many MarR-regulated loci described in the literature. Several studies have described aromatic compounds as effectors of MarR-type regulators 17 . Therefore, the ten anticipated MarR-regulated rdhAB genes in strain CBDB1 are particularly interesting candidates for reductive dehalogenases that dechlorinate aromatic compounds.…”

Benzoate Catabolite Repression of the Phthalate Degradation Pathway in Rhodococcus sp. Strain DK17

“…Successful growth under these conditions depends on the bacterium's ability to quickly choose the best available carbon source and adapt gene expression for efficient metabolism. During the past three decades, much research has centered on elucidating the metabolic pathways for degradation of various aromatic hydrocarbons, and the details of these metabolic pathways at the biochemical and molecular levels have been relatively well documented (5,13,26,27,28). In contrast, very little work has been reported on the degradation of mixtures of aromatic compounds or on the degradation of an individual aromatic hydrocarbon when present in a mixture of structurally similar compounds.…”