Mutant IscR Regulator for Enhanced Iron-Sulfur Cluster Delivery
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Solution Overview
Problem
Current methods for producing biotin, lipoic acid, and thiamine rely on chemical synthesis, which is costly, and biosynthetic pathways in bacterial cell factories face bottlenecks that limit their ability to produce elevated levels of these essential compounds.
Innovation Solution
A genetically modified bacterium with a mutant IscR gene and transgenes encoding biotin synthase, lipoic acid synthase, or HMP-P synthase is used to enhance the production of biotin, lipoic acid, or thiamine, overcoming the limitations by facilitating iron-sulfur cluster assembly and enzyme expression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If biosynthetic pathways are used to produce biotin, lipoic acid, or thiamine in bacterial cell factories, then production cost is reduced compared to chemical synthesis, but the production level is limited by bottlenecks in the biosynthetic pathways
Solution Approach 1:
The invention modifies the regulatory parameters of the biosynthetic pathway by introducing a mutant IscR protein with altered DNA-binding affinity. This parameter change in regulatory binding strength allows derepression of iron-sulfur cluster biosynthesis genes, thereby increasing the availability of clusters for enzymes like BioB and elevating the production level of biotin while maintaining the cost-effective biosynthetic approach
Solution Approach 2:
The mutant IscR protein acts as an intermediary that mediates between the iron-sulfur cluster biosynthesis system and the biotin production pathway. By modifying IscR's regulatory function, the invention enables enhanced delivery of iron-sulfur clusters to BioB enzyme, thereby overcoming the bottleneck in the biotin biosynthetic pathway without requiring complete pathway reconstruction
2Productivity
If the Biosynthetic pathway enzymes are overexpressed to increase production, then productivity is improved, but iron-sulfur cluster delivery becomes the limiting factor
Solution Approach 1:
The invention performs preliminary action by modifying the IscR regulator before the actual biosynthesis step. The mutant IscR is designed to constitutively activate iron-sulfur cluster biosynthesis genes, ensuring that clusters are available in advance for the overexpressed enzymes like BioB, thereby preventing cluster delivery from becoming a limiting factor during high-level production
3Stability of the object's composition
If wild-type IscR is used to regulate iron-sulfur cluster biosynthesis, then cellular homeostasis is maintained, but the delivery of clusters to biosynthetic enzymes like BioB is insufficient for high-level production
Solution Approach 1:
The invention applies local quality by creating a spatial and functional distinction between wild-type IscR and mutant IscR. The mutant IscR is specifically engineered to have enhanced activity toward iron-sulfur cluster biosynthesis genes while maintaining cellular homeostasis through controlled expression. This localized functional enhancement at the regulatory level enables improved cluster delivery to BioB without disrupting overall cellular balance
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 approach significantly increases the production of biotin, lipoic acid, and thiamine, providing a cost-effective alternative to chemical synthesis and addressing the bottlenecks in biosynthetic pathways.
Implementation Method 1
a genetically modified endogenous iscR gene encoding a mutant IscR polypeptide... facilitating iron-sulfur cluster assembly and enzyme expression
Implementation Method 2
transgenes encoding polypeptides that enhance the biosynthesis of either biotin, lipoic acid or thiamine... polypeptide having biotin synthase activity... polypeptide having lipoic acid synthase activity... polypeptide having HMP-P synthase activity
Data Source
AI summary
The invention provides a genetically modified bacterial cell capable of improved iron-sulfur cluster delivery, characterized by a modified gene encoding a mutant Iron Sulfur Cluster Regulator (IscR) as well as one or more transgenes encoding polypeptides that enhance the biosynthesis of either biotin, lipoic acid or thiamine. The invention provides a method for producing either biotin, lipoic acid or thiamine using the genetically modified bacterium of the invention; as well as for the use of the genetically modified bacterial cell for either biotin, lipoic acid or thiamine production.