Optimization of the heme biosynthesis pathway for the production of 5-aminolevulinic acid in Escherichia coli

Abstract

5-Aminolevulinic acid (ALA), the committed intermediate of the heme biosynthesis pathway, shows significant promise for cancer treatment. Here, we identified that in addition to hemA and hemL, hemB, hemD, hemF, hemG and hemH are also the major regulatory targets of the heme biosynthesis pathway. Interestingly, up-regulation of hemD and hemF benefited ALA accumulation whereas overexpression of hemB, hemG and hemH diminished ALA accumulation. Accordingly, by combinatorial overexpression of the hemA, hemL, hemD and hemF with different copy-number plasmids, the titer of ALA was improved to 3.25 g l−1. Furthermore, in combination with transcriptional and enzymatic analysis, we demonstrated that ALA dehydratase (HemB) encoded by hemB is feedback inhibited by the downstream intermediate protoporphyrinogen IX. This work has great potential to be scaled-up for microbial production of ALA and provides new important insights into the regulatory mechanism of the heme biosynthesis pathway.

Improved catalytic activities of a dye-decolorizing peroxidase (DyP) by overexpression of ALA and heme biosynthesis genes in Escherichia coli

“…Heme was also responsible for proteolytic degradation of HemA via the Lon and ClpAP proteases, thus limiting endogenous ALA production [25]. Recent studies on heme regulation revealed that endogenous HemA and HemL are part of a C 5 pathway that is tightly regulated by the downstream genes particularly via ALA dehydratase, encoded by hemB gene that is considered as a key feedback inhibitory node in the heme synthesis pathway [26]. By contrast, intracellular ALA biosynthesis was successfully increased in the pHemAL-DyP strain.…”

Purification and functional characterization of thermostable 5-aminolevulinic acid synthases

“…Introduction 5-Aminolevulinic acid (ALA), the precursor for the biosynthesis of tetrapyrroles, has received extensive attention because of its broad applications in the fields of agriculture and medicine (Zhang et al 2015). Many researches have been carried out for biological production of ALA using recombinant Escherichia coli strains expressing heterogeneous 5-aminolevulinic acid synthase (ALAS), the key enzyme in ALA synthesis.…”

Influence of Glycine, Succinate, Levulinic Acid and Glutamate Concentrations on Growth of Purple Non-Sulfur Photosynthetic Bacteria and 5-Aminolevulinic Acid Production

“…palustris, as well as oxygenic photosynthetic bacteria, such as Anacystis nidulans are also reported [1]. It is well known that photosynthetic bacteria have the ability to synthesize tetrapyrrol via 5-ALA intracellularly from glycine and succinate by ALA-synthetase (Shemin pathway) [14,15,26]. Wild strains have very low yield of 5-ALA, so optimization of the production is needed.…”