Local metabolic response of Escherichia coli to the module genetic perturbations in L-methionine biosynthetic pathway

iota-Methionine biosynthesis is through multilevel regulated and multibranched biosynthetic pathway (MRMBP). Because of the complex regulatory mechanism and the imbalanced metabolic flux between branched pathways, mi-crobial production of iota-methionine has not been commercialized. In this study, local metabolic response in MRMBP of iota- methionine was investigated and various crucial genes in branched pathways were determined. In iota-serine pathway, the crucial gene was serABC. In O-succinyl homoserine (OSH) pathway, which was the C4 backbone of iota-methionine, metB and metL controlled the metabolic flux jointly. In iota-cysteine pathway, the crucial gene cysEfbr could disturb the flux distribution of local network in iota-methionine biosynthesis. However, no crucial gene for iota-methionine production in 5 -methyl tetrahydrofolate (CH3-THF) pathway was found. The relation between these pathways was also researched. iota- Serine pathway, as the upstream pathway of iota-cysteine and CH3-THF, played a crucial role in iota-methionine biosynthesis. iota- Cysteine pathway showed the strongest controlling force of the metabolic flux, and OSH pathway was second to iota- cysteine pathway. In contrast, CH3-THF pathway was the weakest, which was probably the mainly limited steps at present and had great potential in further research. In addition, constructed W3110 IJAHFEBC/pA*HAmL was able to produce 2.62 g/iota iota-methionine in flask. This study is instructive for iota-methionine biosynthesis and provides a new research method of biosynthesizing other metabolic products in MRMBPs. (c) 2023, The Society for Biotechnology, Japan. All rights reserved.

Automated summary

This study investigates the metabolic response and crucial genes in the biosynthetic pathway of iota-methionine. The relationship between different pathways and their controlling forces on metabolic flux are also examined. The findings provide insights into the biosynthesis of iota-methionine and offer a new research method for synthesizing other metabolic products in multilevel regulated and multibranched biosynthetic pathways.