Characterization of divergent promoters PmaiA and Phyd from Gordonia: Co-expression and regulation by CRP

Jaishankar, Jananee; Keshav, Aditi; Jayaram, Bijjiga; Chavan, Sourabh; Srivastava, Preeti

doi:10.1016/j.bbagrm.2022.194843

Cited by 2 publications

(1 citation statement)

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“…Maleate isomerase (MaiA) (maleate cis-trans isomerase), belonging to the superfamily of Asp/Glu racemase, could catalyze the isomerization of maleate to fumarate and has been identified in many bacteria, such as Pseudomonas, Alcaligenes, Serratia, Proteus, Bacillus, and Deleya halophile . The crystal structure of the MaiA (NfMI) from Nocardia farcinica IFM 10152 shows that Cys76 is involved in the nucleophilic attack in the initial reaction .…”

Section: Introductionmentioning

confidence: 99%

One-Pot Biosynthesis of l-Aspartate from Maleic Anhydride via a Thermostable Dual-Enzyme System under High Temperature

liu

Zong

Wang

et al. 2022

J. Agric. Food Chem.

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l-Aspartate is an important chemical in the food and pharmaceutical industries. Herein, a dual-enzyme system was constructed to synthesize l-aspartate from maleic anhydride at 50 °C, which can reduce the byproduct production. Maleate transformed from maleic anhydride in the solution was converted into l-aspartate via fumarate catalyzed by maleate isomerase (MaiA) and thermostable aspartase (AspB), respectively. Because MaiA is a rate-limiting enzyme, enzyme activities of various MaiAs were compared, and the efficient and thermostable maleate isomerase AaMaiA from Alicyclobacillus acidoterrestris was chosen. The K cat/K m value of AaMaiA was 264.4 mM–1 min–1. AaMaiA and AspB were coexpressed in E. coli to produce l-aspartate. To improve the l-aspartate production rate, the ribosome binding site (RBS) sequence located upstream of AaMaiA was optimized and the Tat signal peptide was fused with AaMaiA. The conversion rate was 96% within 60 min, and the intermediate was not detected, the possible reason of which is that high temperature inhibits the activity of bacterial endogenous enzymes, but functional enzymes remain active. Cells from fermentation produced 243.6 g/L (1.83 M) of l-aspartate with a 2 M substrate. Our study revealed an effective method to produce l-aspartate without using gene knockout and provided a strategy for l-aspartate production in the industrial field.

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