Modified Sigma Factor 70 Polypeptide for L-Threonine Production
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Solution Overview
Problem
Current methods for producing L-threonine using microorganisms often result in growth retardation of host cells and suboptimal yields, limiting the efficiency and cost-effectiveness of the production process.
Innovation Solution
A novel modified sigma factor 70 polypeptide of RNA polymerase is introduced into Escherichia sp. to enhance L-threonine production, specifically by substituting certain amino acids in the sigma factor 70 protein, which leads to improved transcriptional regulation and increased L-threonine yields without growth inhibition of the host cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If random mutations are introduced on sigma factor 70 to enhance L-threonine production, then productivity is improved, but host cell growth is retarded
Solution Approach 1:
The patent applies parameter changes by systematically mutating specific amino acid residues at defined positions (440-450, 459, 466, 470-479, 484, 495-499, 509, 527, 565-570, 575-580, 599, and 612) in the sigma factor 70 protein. This targeted approach modifies transcriptional regulation parameters to enhance L-threonine production while maintaining host cell growth capability, resolving the contradiction between productivity improvement and cellular health.
2Productivity
If conventional mutation methods are used to develop L-threonine producing strains, then production capability is enhanced, but the process becomes time-consuming and costly
Solution Approach 1:
The patent implements preliminary action by pre-identifying and targeting specific amino acid positions in the sigma factor 70 that are most likely to influence L-threonine production. Rather than performing random mutagenesis followed by extensive screening, the invention directly modifies predetermined positions, significantly reducing the time and resources required for strain development while achieving enhanced production capability.
3Productivity
If global transcription machinery engineering is applied to regulate all intracellular genes, then productivity is improved, but device complexity and process difficulty increase
Solution Approach 1:
The patent applies local quality by focusing transcriptional regulation modifications specifically on the sigma factor 70, which controls housekeeping genes including those involved in L-threonine biosynthesis. Instead of attempting to regulate all intracellular genes globally, the invention locally targets the sigma factor to achieve productive enhancement with simplified regulatory complexity.
Data Source
AI summary
The present invention relates to a novel variant RNA polymerase sigma factor 70 (σ70) polypeptide, a polynucleotide encoding the same, a microorganism containing the polypeptide, and a method for producing L-threonine by using the microorganism.