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Genetic organization, nucleotide sequence and regulation of expression of genes encoding phenol hydroxylase and catechol 1,2‐dioxygenase in Acinetobacter calcoaceticus NCIB8250
Author(s) -
Ehrt Sabine,
Schirmer Falck,
Hillen Wolfgang
Publication year - 1995
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1995.mmi_18010013.x
Subject(s) - biology , acinetobacter calcoaceticus , operon , gene , nucleic acid sequence , genetics , open reading frame , microbiology and biotechnology , peptide sequence , escherichia coli , acinetobacter , bacteria
We have mutated Acinetobacter calcoaceticus NCIB8250 to growth deficiency on phenol as sole carbon source and isolated genes with similarity to phenol hydroxylase and catechol 1,2‐dioxygenase by complementation. Sequence analysis reveals the presence of six open reading frames (ORFs) with similarities to a Pseudomonas multicomponent phenol hydroxylase which are followed by an ORF with similarity to catA from A. calcoaceticus ADP1. Transformation of these genes to ADP1 confers the ability to grow at the expense of phenol as sole carbon source. Primer extension analysis indicates phenol‐inducible transcription from an RpoN‐dependent promoter sharing sequence similarity with the σ 54 consensus promoter sequence, except that the −12 box is GG instead of GC. A catA :: lacZ transcriptional fusion shows the same induction profile for β‐galactosidase expression as transcription from the σ 54 ‐dependent promoter. This result suggests that catA is cotranscribed in the same operon with the phenol hydroxylase‐encoding genes and is consistent with the fact that no apparent additional promoter is found for catA by sequence analysis or primer extension. Catechol 1,2‐dioxygenase activity is induced in NCIB8250 by benzoate, whereas β‐galactosidase expression from the catA :: lacZ fusion is not. This observation leads to the hypothesis that two differentially regulated catA genes should be present in that strain.