Characterization and expression of C4-dicarboxylate binding protein coding gene dctP of the nitrogen fixing bacterium Pseudomonas stutzeri A1501

Abstract:

[Objective] Current study was designed to determine the functional characterization and expression pattern of C4-dicarboxylate binding protein coding gene dctP in nitrogen fixing bacterium Pseudomonas stutzeri A1501. [Methods] We constructed the nonpolar dctP mutant. The nitrogenase activity and growth curve between the wild type and mutants were assayed in minimal medium supplemented with different C4-dicarboxylates (succinate, malate or fumarate) as a sole carbon source were measured. The dctP-lacZ fusion vector was constructed and transformed to wild type A1501, dctB mutant, rpoN mutant and ntrBC mutant, respectively. The β-galactosidase activity was detected to analyze the expression of dctP gene in recombinant strains grown with different C4-dicarboxylates as a sole carbon source. [Results] It was found that dctP mutant lost the ability to utilise C4-dicarboxylates and its nitrogenase activity was much lower than the wild type. The analysis of β-galactosidase activity indicated that the succinate, malate or fumarate induced expression of the dctP gene. In comparison with wild type, the expression level of dctP gene was significantly decreased in the deletion mutants for dctB, rpoN or ntrBC. [Conclusion] The DctP protein played an important role in the C4-dicarboxylate utilization of P. stutzeri A1501. C4-dicarboxylates (succinate, malate or fumarate) induced the expression of dctP gene. The DctP transcription was RpoN-dependent and under the control of DctB and NtrBC.

Key words:Pseudomonas stutzeri A1501, C4-dicarboxylates, DctP