Modified Sigma Factor 70 Polypeptide for L-Threonine Production
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Solution Overview
Problem
Current methods for producing L-threonine in microorganisms often result in growth retardation of the host cell and do not efficiently enhance productivity, limiting the yield and economic viability of the production process.
Innovation Solution
Development of a modified sigma factor 70 polypeptide of RNA polymerase with specific amino acid substitutions, which is introduced into Escherichia sp. to enhance L-threonine production without affecting cell growth, involving the use of a transformed microorganism that expresses this modified polypeptide and a method for culturing and recovering L-threonine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to enhance L-threonine production in microorganisms, then productivity is improved, but host cell growth is retarded
Solution Approach 1:
The invention modifies the sigma factor 70 protein by changing specific amino acid residues (K440R, Q446P, R448S, M474V, E477G, A484V, K496N, L498R, T509M, T527P, M567V, T569P, N576G, Q579R, R599C, D612G) to alter the transcriptional regulation parameters. This parameter change enables enhanced L-threonine production while maintaining normal host cell growth, resolving the contradiction between productivity improvement and growth retardation
Solution Approach 2:
The invention applies local quality modification by specifically targeting and mutating particular amino acid residues within the sigma factor 70 protein structure. These localized changes at specific positions (440, 446, 448, 474, 477, 484, 496, 498, 509, 527, 567, 569, 576, 579, 599, 612) create the desired effect of enhanced threonine production without disrupting overall cellular function and growth
Data Source
AI summary
The present invention relates to a novel variant RNA polymerase sigma factor 70 (δ70) polypeptide, a polynucleotide encoding the same, a microorganism containing the polypeptide, and a method for producing L-threonine by using the microorganism.