Modified Diguanylate Cyclase Enzyme for Efficient c-di-GMP Synthesis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for enzymatic synthesis of c-di-GMP, such as using GsDGC from Geobacillus stearothermophilus, face challenges including low enzyme activity, the need for significant culture medium, enzyme purification, and complex procedures, making them unsuitable for industrial-scale production.
Innovation Solution
A novel modified diguanylate cyclase enzyme, tiGs3466, with enhanced specific activity, productivity, and thermal stability is developed by mutating the 54th residue asparagine to glycine and introducing mutations in the i-site, allowing for efficient c-di-GMP synthesis without the need for extensive purification or large culture media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional enzymatic synthesis methods using GsDGC are employed, then c-di-GMP can be synthesized, but the enzyme activity is low and significant amounts of culture medium are required
Solution Approach 1:
The patent applies parameter changes by mutating specific amino acid residues in the GsDGC enzyme sequence. The N54G mutation (asparagine to glycine at position 54) and i-site mutations (K311A, D314N, or K311A/D314N combination) were introduced to modify enzyme properties. These parameter changes in the enzyme structure resulted in dramatically enhanced specific activity (approximately 40-fold increase) and improved thermal stability, thereby resolving the contradiction between productivity and the quantity of culture medium required.
2Productivity
If conventional enzymatic synthesis methods are used, then c-di-GMP can be produced, but the process requires enzyme purification and complex procedures
Solution Approach 1:
The patent employs a disposable crude enzyme solution derived from E. coli cells expressing the modified GsDGC. Instead of requiring purification of the enzyme, the invention uses the crude extract directly for c-di-GMP synthesis. This approach eliminates complex purification steps while maintaining high productivity, as the modified enzyme retains sufficient activity and stability in the crude form. The enzyme solution can be prepared in advance and stored, simplifying the overall process.
3Productivity
If conventional enzymatic synthesis methods are employed, then c-di-GMP synthesis can proceed, but the procedure is complex and not suitable for industrial-scale production
Solution Approach 1:
The patent applies preliminary action by pre-modifying the GsDGC enzyme with specific mutations (N54G and i-site mutations) before use in the synthesis reaction. The modified enzyme exhibits enhanced stability and activity, allowing the synthesis procedure to be simplified. The crude enzyme solution can be prepared in advance through simple expression in E. coli, and the actual c-di-GMP synthesis requires only the addition of substrates (GTP or GMP with polyphosphate) and incubation, eliminating the need for complex step-by-step procedures during production.
4Productivity
If GTP is used as substrate, then c-di-GMP can be synthesized directly, but substrate inhibition occurs requiring frequent GTP addition
Solution Approach 1:
The patent introduces an intermediary system by using GMP and polyphosphate as substrates instead of direct GTP addition. The modified GsDGC enzyme works in conjunction with nucleoside diphosphate kinase (NDK) to convert GMP and polyphosphate into GTP in situ, which then serves as the substrate for c-di-GMP synthesis. This intermediary approach eliminates substrate inhibition problems associated with high GTP concentrations and removes the need for frequent GTP addition, as the GMP and polyphosphate can be added once at the beginning of the reaction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified enzyme significantly improves c-di-GMP synthesis efficiency, enabling practical industrial-scale production with a crude enzyme solution and reducing the amount of bacterial cells required, thus simplifying the process and lowering costs.
Implementation Method 1
C-di-GMP can be synthesized from two GTP molecules by a two-step enzymatic reaction via the catalytic action of a diguanylate cyclase (hereinafter, sometimes called 'DGC'). The modified enzyme tiGs3466 with enhanced specific activity, productivity, and thermal stability is developed by mutating the 54th residue asparagine to glycine and introducing mutations in the i-site
Data Source
AI summary
A practical method for enzymatically synthesizing c-di-GMP with excellent productivity is provided. A diguanylate cyclase having physical and chemical characteristics (A) to (F): (A) catalytic action on reaction “2 GTP→c-di-GMP”; (B) a molecular weight of 19800±2000; (C) an optimum pH of 7.3 to 9.4; (D) an optimum temperature of 35 to 60° C.; (E) thermal stability as the remaining activity of 90% or higher after heated for 60 minutes under conditions of 50° C. and pH7.8; and (F) the presence of GGDEF (SEQ ID NO:26) domain and the lack of amino acid sequence KXXD (SEQ ID NO:23) in the i-site.