Regulation mechanism of the long-chain <i>n</i> -alkane monooxygenase gene <i>almA</i> in <i>Acinetobacter venetianus</i> RAG-1

The extreme hydrophobicity of long-chain <i>n</i>-alkanes ({greater than or equal to}C₂₀) presents a significant challenge to their degradation in natural environments. It is, therefore, imperative to elucidate the regulatory mechanisms of the metabolic pathways of long-chain <i>n</i>-alkanes, which will be of great significance for the future application of hydrocarbon-degrading bacteria to treat oil spills. However, the majority of current studies have focused on the regulatory mechanisms of short- and medium-chain <i>n</i>-alkanes, with long-chain <i>n</i>-alkanes receiving comparatively little attention. In this study, we identified APR1, a transcriptional regulator of the alkane monooxygenase AlmA in <i>Acinetobacter venetianus</i> RAG-1, and characterized its function and regulatory mechanism. In the presence of ligand <i>n</i>-C₃₂, APR1 could directly activate the transcription of <i>almA</i>, which was involved in the <i>n</i>-C₃₂ metabolism. The amino acid residue unique to the C-terminal DNA-binding domain of AraC/XylS type <i>n</i>-alkanes transcription regulators was also identified. These findings further improved our understanding of the long-chain <i>n</i>-alkanes degradation mechanism, which is important for the management of petroleum pollution.