PHA Synthase Mutants for Lactyl-CoA Polymerization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing high molecular weight polylactate (PLA) are complex and inefficient, particularly in using lactyl-CoA as a substrate for polyhydroxyalkanoate synthase, which results in low synthesis efficiency for PLA and lactate copolymers due to weak PHA synthase activity on lactyl-CoA.
Innovation Solution
Development of polyhydroxyalkanoate synthase mutants from Pseudomonas sp. 6-19 with specific amino acid mutations, such as E130D and Q481K, that can efficiently use lactyl-CoA to produce lactate polymer and copolymer, along with a recombinant vector system including propionyl-CoA transferase for substrate conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional PHA synthase is used to polymerize lactyl-CoA, then the process can be simplified compared to chemical synthesis methods, but the synthesis efficiency is very low due to weak PHA synthase activity on lactyl-CoA
Solution Approach 1:
The patent applies parameter changes by introducing specific amino acid mutations (E130D, Q481K, S325T, S477R, S477H, S477F, S477Y) into the PHA synthase enzyme to alter its substrate specificity and enzymatic activity. These mutations modify the enzyme's active site to recognize and bind lactyl-CoA more effectively, transforming it from a enzyme with weak activity on this substrate to one with high catalytic efficiency, thereby resolving the contradiction between process simplicity and synthesis efficiency
Solution Approach 2:
The patent uses a recombinant vector system to copy and express the mutated PHA synthase gene in host cells. The gene encoding the mutant enzyme is cloned into a vector and introduced into bacterial cells, allowing mass production of the high-efficiency enzyme. This copying approach enables the engineered enzyme with improved lactyl-CoA activity to be produced at scale, maintaining process simplicity while dramatically improving productivity
2Device complexity
If wild-type PHA synthase is used, then the enzyme structure is simple and well-characterized, but it cannot efficiently use lactyl-CoA as a substrate resulting in low polymer production
Solution Approach 1:
The patent modifies specific parameters of the enzyme structure through targeted amino acid mutations at positions E130, Q481, S325, S477, and S477. These parameter changes in the enzyme's primary structure alter its substrate binding characteristics, enabling efficient recognition and polymerization of lactyl-CoA. The mutations are introduced using site-directed mutagenesis, allowing precise control over the enzyme's functional properties while maintaining overall structural simplicity
Solution Approach 2:
The patent segments the enzyme improvement process into distinct functional regions: the catalytic domain, the substrate binding domain, and the structural framework. By introducing mutations selectively in specific segments (particularly in the active site and substrate binding regions), the patent achieves high polymer production without requiring complete redesign of the entire enzyme structure, thus maintaining structural simplicity while dramatically increasing quantity of substance produced
3Adaptability or versatility
If propionyl-CoA transferase is added to provide lactyl-CoA, then the substrate availability is improved, but the system complexity increases due to additional enzyme requirement
Solution Approach 1:
The patent merges the propionyl-CoA transferase enzyme with the PHA synthase system into an integrated metabolic pathway. Both enzymes are co-expressed in the host cell, and their functions are coordinated to convert propionyl-CoA to lactyl-CoA and then to poly(lactate). This merging approach ensures continuous substrate availability while managing system complexity through coordinated enzymatic action rather than separate independent systems
Solution Approach 2:
The patent employs a universal recombinant expression system that can simultaneously express multiple enzymes (PHA synthase with various mutations and propionyl-CoA transferase) in a single host cell. This multi-functional system allows the cell to perform both substrate conversion (propionyl-CoA to lactyl-CoA) and polymerization functions, improving substrate availability while managing complexity through a unified expression and metabolic control framework
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 mutants significantly enhance the synthesis efficiency of lactate polymers and copolymers, allowing for the production of high molecular weight PLA and lactate copolymers with improved substrate specificity and molecular weight, overcoming the limitations of existing methods.
Implementation Method 1
PHA synthase which synthesizes the PHA polymer using the PHA monomers are required. When producing PLA and lactate copolymer with microorganisms, the same system is needed and an enzyme being able to provide lactyl-CoA also is needed in addition to an enzyme providing hydroxyacyl-CoA
Implementation Method 2
the present inventors developed a system using propionyl-CoA transferase originated from Clostridium propionicum to provide lactyl-CoA
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The present invention relates to polyhydroxyalkanoate synthase (PHA synthase) mutant originated from Pseudomonas sp. 6-19 (KCTC 11027BP) which can prepare lactate polymer and/or copolymer by using lactyl-CoA as a substrate. The present invention relates to a method for preparing lactate polymer and/or copolymer with the synthase mutant. The polyhydroxyalkanoate synthase mutants of the present invention originated from Pseudomonas sp. 6-19 can efficiently prepare lactate polymer and/or copolymer by using as a substrate lactyl-CoA which is difficult to be used as a substrate by conventional polyhydroxyalkanoate synthase.