Role of sigma 54 and bamVW in regulation of anaerobic aromatic degradation via benzoate-CoA ligase by Geotalea daltonii

Benzoate, an aromatic compound, is anaerobically activated by benzoate-coenzyme A (CoA) ligase, yielding benzoyl-CoA, a central intermediate into which many aromatic compounds are converted before entering the benzoyl-CoA pathway. This study elucidated modulation of benzoate-CoA ligase gene bamY , particularly the role of BamVW and σ 54 in its transcription in Geotalea daltonii strain FRC-32 . The two-component system (TCS) genes bamV, encoding a histidine kinase, bamW , encoding a σ 54 -dependent response-regulator, the xylR- like gene, encoding a σ 54 -dependent enhancer-binding protein, and the σ 54 -dependent pY promoter upstream of bamY , encoding benzoate-CoA ligase, were identified via genomic analysis. Arrangement of bamVW and a xylR- like gene in an operon suggested that BamVW functions as σ 54 -dependent kinase-regulator pair. Expression levels for bamVW, bamY, and rpoN, encoding σ 54 , were significantly higher in benzoate-oxidizing cultures compared to those in benzene- and toluene-oxidizing cultures, suggesting that these genes are essential in anaerobic benzoate oxidation by G. daltonii . The transcription start site of bamY was identified, and binding of σ 54 to the pY promoter was confirmed. Our results suggested that regulation of bamY is σ 54 -dependent and that BamVW and σ 54 are essential in initiating transcription of bamY in anaerobic aromatic oxidation by G. daltonii. The findings of our study hold significant potential for improving anaerobic aromatic biodegradation efficiency. • bamV and bamW functioned in modulation of benzoate CoA-ligase bamY in G. daltonii • σ 54 promoted transcriptional regulation of benzoate CoA-ligase bamY in G. daltonii • σ 54 played a central role during anaerobic aromatic degradation in G. daltonii