Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, No 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China.
School of Biotechnology, Jiangnan University, No 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China.
Biotechnol Lett. 2022 Feb;44(2):271-277. doi: 10.1007/s10529-021-03212-z. Epub 2021 Nov 26.
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.
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.
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.
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.
研究 5-氨基乙酰丙酸（5-ALA）作为血红素关键前体的水平，以及血红素过氧化物酶的表达对大肠杆菌中血红素合成的调节作用。
敲除转运基因（eamA），并过表达 5-ALA 合成的谷氨酰-tRNA 还原酶基因（hemA）和染料脱色过氧化物酶基因（DyP）。
敲除 eamA 导致 5-ALA 分泌减少，表明 EamA 参与 5-ALA 的转运。hemA 的过表达提高了细胞内 5-ALA 和血红素水平。然而，hemA 在 eamA 敲除突变体中的过表达导致细胞内血红素含量下降，并使血红素合成基因 hemL 的转录下调约 5.2 倍。当在突变体中同时过表达 hemA 和 DyP 时，hemL 上调，表明血红素与 DyP 的结合释放了对 hemL 的反馈抑制。
HemL 的表达受血红素调控，血红素过氧化物酶过表达使游离血红素在细胞内固定，有助于理解和应用血红素调控。
