Chimeric CcmC Protein for Minimized Carboxysome Assembly
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Solution Overview
Problem
Current methods have not successfully generated functional multi-protein metabolic carboxysome cores, which are essential for carbon fixation in cyanobacteria, as they require the assembly of multiple proteins and complex interactions.
Innovation Solution
A chimeric protein, CcmC, is designed by fusing key domains from four proteins into a single protein that assembles into a functional carboxysome core, including small subunit-like domains, carbonic anhydrase, and an encapsulation peptide, allowing for the creation of a streamlined carboxysome core that can be transferred and utilized in other organisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple proteins are assembled to form a functional carboxysome core, then the carbon fixation function is achieved, but the device complexity and difficulty of assembly increase
Solution Approach 1:
The patent combines multiple carboxysome core proteins (CcmM, CcmN, CcaA, and Rubisco) into a single chimeric protein CcmC. This fusion protein contains the small subunit-like domains from CcmM, carbonic anhydrase domain from CcaA, and encapsulation peptide from CcmN, all integrated into one polypeptide chain that can self-assemble into functional carboxysome cores without requiring separate expression and assembly of multiple individual proteins.
Solution Approach 2:
The chimeric protein CcmC performs multiple functions that were previously distributed across separate proteins: it provides structural scaffolding (via SSLDs), catalytic activity (via carbonic anhydrase domain), and assembly guidance (via encapsulation peptide). This multi-functional design simplifies the system while maintaining all essential carboxysome functions.
2Reliability
If multiple proteins are expressed for carboxysome assembly, then functional carboxysomes are formed, but the genomic load increases
Solution Approach 1:
The patent merges the genetic information for multiple carboxysome proteins into a single gene encoding the chimeric CcmC protein. This reduces the number of genomic elements required from multiple separate genes to a single fusion gene, thereby reducing genomic load while maintaining the ability to produce all necessary functional domains.
3Ease of manufacture
If a streamlined carboxysome core is created using a single chimeric protein, then the genomic load is reduced and assembly is simplified, but the complexity of protein design increases
Solution Approach 1:
The chimeric protein CcmC is designed by segmenting and fusing specific functional domains from different proteins: small subunit-like domains (SSLDs) from CcmM for structural function, carbonic anhydrase domain from CcaA for catalytic activity, and encapsulation peptide from CcmN for assembly guidance. This domain-level segmentation allows systematic design while maintaining functional modularity.
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 CcmC protein enables efficient carbon fixation by concentrating CO2 into useful carbon-containing molecules like 3-phosphoglycerate, supporting photosynthesis and reducing the genomic load required for carboxysome assembly, while maintaining functional and morphological similarity to native carboxysomes.
Implementation Method 1
In the carboxysome lumen, bicarbonate is converted into carbon dioxide by carbonic anhydrase. Such conversion increases the proportion of carbon dioxide to oxygen in the vicinity of Rubisco
Implementation Method 2
The at least two small subunit-like domains (SSLDs) from a carbon dioxide concentrating mechanism (CcmM) protein can bind or nucleate with ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco)
Implementation Method 3
The at least one encapsulation peptide can interact with, nucleate, and/or bind one or more carboxysome shell protein
Implementation Method 4
The Rubisco can, for example, synthesize 3-phosphoglycerate (3-PGA)
Data Source
AI summary
A fusion chimeric protein is described herein that can assemble a functional carboxysome core, which is able to fix carbon by taking atmospheric carbon dioxide and converting it into useful carbon-containing compounds such as 3-phosphoglycerate (3-PGA).