Mutant PETase Thermostability via Salt Bridge Stabilization
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Solution Overview
Problem
Current PETases lack sufficient thermostability and activity for efficient biodegradation of polyethylene terephthalate at higher temperatures, limiting their effectiveness in plastic recycling.
Innovation Solution
Development of mutant PETase variants with specific amino acid mutations, such as S93R and S93K, that form stabilizing interactions like salt bridges, enhancing thermostability and activity by maintaining enzyme stability at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher temperatures are used to increase PETase activity, then degradation rate improves, but enzyme stability deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying amino acid residues at specific positions (93, 158, and 280) in the PETase enzyme sequence. These mutations change the chemical parameters of the enzyme to form stabilizing interactions (salt bridges and hydrogen bonds) that maintain enzyme structure and activity at higher temperatures, thereby resolving the contradiction between degradation rate and enzyme stability.
2Reliability
If mutations are introduced to stabilize the β6-β7 connecting loop, then thermostability improves, but the expected hydrogen bond stabilization fails
Solution Approach 1:
The patent applies local quality by making specific localized changes at positions 93, 158, and 280 in the enzyme sequence. These localized mutations create salt bridges and hydrogen bonds that stabilize the β6-β7 connecting loop region, achieving thermostability through targeted local modifications rather than global structural changes.
Solution Approach 2:
The patent converts the previously failed approach of introducing mutations into a successful solution by carefully selecting specific amino acid substitutions (S93R/K, D158E, R280A) that create stabilizing salt bridges. What was initially a failed attempt at hydrogen bond stabilization becomes a successful thermostability solution through the formation of salt bridge interactions.
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 mutant PETases exhibit higher thermostability and activity compared to wild-type enzymes, enabling more efficient degradation of polyethylene terephthalate even at 60°C, making them suitable for industrial recycling applications.
Implementation Method 1
The high thermostability is proposed to be due to a single mutation which is capable of stabilizing the β6-β7 connecting loop by forming a stabilising interaction, such as a salt bridge
Implementation Method 2
Son et al., 2019 hypothesized that mutations of these positions in the PETase would lead to stabilization of the β6-β7 connecting loop by formation of hydrogen bonds
Implementation Method 3
PETases have the ability to substantially decrease the amount of time that it takes to degrade plastics, thereby making biodegradation a viable option for plastic recycling
Data Source
AI summary
The present disclosure relates to engineered polypeptides capable of degrading a polymer, such as polyethylene terephthalate (PET). The present disclosure also discloses polynucleotides encoding the polypeptides, vectors comprising the polynucleotides, as well as cells expressing the polynucleotides or vectors comprising the polynucleotides. Disclosed are also methods of degrading polymers, such as PET, and methods of manufacturing terephthalic acid and ethylene glycol.