A peculiar IclR family transcription factor regulates para-hydroxybenzoate catabolism in Streptomyces coelicolor
AffiliationUniv Arizona, Dept Chem & Biochem
MetadataShow full item record
PublisherOXFORD UNIV PRESS
CitationA peculiar IclR family transcription factor regulates para-hydroxybenzoate catabolism in Streptomyces coelicolor 2018, 46 (3):1501 Nucleic Acids Research
JournalNucleic Acids Research
Rights© The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research. This is an Open Access article distributed under the terms of the Creative Commons Attribution License.
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AbstractIn Streptomyces coelicolor, we identified a para-hydroxybenzoate (PHB) hydroxylase, encoded by gene pobA (SCO3084), which is responsible for conversion of PHB into PCA (protocatechuic acid), a substrate of the beta-ketoadipate pathway which yields intermediates of the Krebs cycle. We also found that the transcription of pobA is induced by PHB and is negatively regulated by the product of SCO3209, which we named PobR. The product of this gene is highly unusual in that it is the apparent fusion of two IcIR family transcription factors. Bioinformatic analyses, in vivo transcriptional assays, electrophoretic mobility shift assays (EMSAs), DNase I footprinting, and isothermal calorimetry (ITC) were used to elucidate the regulatory mechanism of PobR. We found that PobR loses its high affinity for DNA (i.e., the pobA operator) in the presence of PHB, the inducer of pobA transcription. PHB binds to PobR with a K-D of 5.8 mu M. Size-exclusion chromatography revealed that PobR is a dimer in the absence of PHB and a monomer in the presence of PHB. The crystal structure of PobR in complex with PHB showed that only one of the two IclR ligand binding domains was occupied, and defined how the N-terminal ligand binding domain engages the effector ligand.
NoteOpen access journal.
VersionFinal published version
SponsorsNSF CAREER [MCB1053319, MCB0952550]; Office of Vice President for Research at Brown University; Brown University; University of Arizona