Objectives: To investigate the level of 5-aminolevulinic acid (5-ALA), a key precursor of heme, and expression of heme-peroxidase on the regulation of heme synthesis in E. coli.
Methods: A transporter gene (eamA) was knocked out, and glutamyl-tRNA reductase gene (hemA) for 5-ALA synthesis and a dye-decolorizing peroxidase gene (DyP) were overexpressed.
Results: Knockout of eamA caused decrease of 5-ALA secretion, indicating EamA participates in 5-ALA transportation. Overexpression of hemA elevated intracellular 5-ALA and heme levels. However, overexpression of hemA in eamA knockout mutant led to decrease of intracellular heme content and down-regulation of the transcription of heme synthetic gene hemL by ~ 5.2-fold. When overexpressing both hemA and DyP in the mutant, hemL was up-regulated suggesting the binding of heme to DyP released the feedback repression of hemL.
Conclusion: HemL expression is heme-mediated and the approach of intracellular immobilization of free heme by overexpression of heme-peroxidase benefits the understanding and application of heme regulation.
Keywords: 5-Aminolevulinic acid; Dye-decolorizing peroxidase; Escherichia coli; Glutamyl-tRNA reductase; Heme.
© 2021. The Author(s), under exclusive licence to Springer Nature B.V.