Monomeric Streptavidin Gene Construct for Targeted Cancer Therapy
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Solution Overview
Problem
Current cancer treatments face challenges due to the unclear mechanism of cancer development, high costs of diagnosis and chemotherapy, and the limitations of monomeric streptavidin proteins in maintaining biotin binding activity and stability for clinical use, particularly their rapid degradation in serum.
Innovation Solution
A gene construct comprising a monomeric streptavidin (mSA) gene, a maltose-binding protein (MBP) gene, and a regulatory gene that enhances expression and stability of mSA, allowing it to be expressed in the periplasm of host cells, where it maintains functionality and binds specifically to biotin, facilitating targeted cancer therapy and diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tetrameric streptavidin is used, then high binding affinity for biotin is achieved, but unwanted cross-linking of biotin conjugates occurs
Solution Approach 1:
The patent divides the tetrameric streptavidin structure into monomeric units by introducing a mutation at position 11 (R11A) that prevents tetramer formation. This segmentation maintains the biotin binding capability of individual monomers while eliminating the cross-linking problem associated with tetrameric structures.
Solution Approach 2:
The patent changes the structural parameter of streptavidin from tetrameric to monomeric form through specific amino acid mutation. This parameter change preserves the essential biotin binding function while removing the harmful cross-linking property, achieving a balance between functionality and safety.
2Object-generated harmful factors
If monomeric avidin-like proteins are developed, then cross-linking problem is solved, but rapid degradation in serum occurs
Solution Approach 1:
The patent creates a composite protein structure by fusing streptavidin monomer with a stable carrier protein (such as albumin or immunoglobulin). This composite construction provides the monomeric streptavidin with the stability and serum resistance of the carrier protein while maintaining its biotin binding specificity and preventing cross-linking.
3Reliability
If monomeric streptavidin is expressed in host cells, then biotin binding activity is maintained, but high-purity protein production requires complex purification processes
Solution Approach 1:
The patent introduces a fusion tag or carrier protein as an intermediary that facilitates the expression and purification of monomeric streptavidin. The carrier protein serves as a soluble, stable platform that enables easy extraction and purification of the fused monomeric streptavidin, eliminating the need for complex purification procedures while maintaining protein activity.
4Reliability
If tetrameric streptavidin is used, then biotin binding function is achieved, but social and economic burden increases due to high treatment costs
Solution Approach 1:
The patent employs monomeric streptavidin with a shortened half-life in serum compared to tetrameric forms. This shorter circulating time reduces the total dose required for effective treatment, thereby lowering treatment costs. The monomeric form achieves sufficient biotin binding function while being more cost-effective due to reduced protein dosage requirements.
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 recombinant vector expressing mSA in host cells achieves high productivity and maintains biotin binding activity in vivo, enabling effective targeting and treatment of cancer tissues with biotinylated drugs and diagnostic agents.
Implementation Method 1
streptavidin and avidin proteins are proteins having a high binding affinity for biotin, and if their specific interaction with biotin is used, they may be applied to various biological applications
Implementation Method 2
a regulatory gene that regulates the expression of the gene encoding monomeric streptavidin
Implementation Method 3
a gene encoding maltose-binding protein (MBP)... the gene encoding monomeric streptavidin... expressed in the periplasm of host cells
Data Source
AI summary
The present invention relates to a monomeric streptavidin-expressing gene construct and a host cell into which a recombinant vector comprising the gene construct has been introduced. The gene construct according to the present invention, after injected in vivo through a strain, may express streptavidin, thereby making it possible not only to monitor in real time the location of the strain or a cancer tissue pre-targeted by the strain by using a biotinylated diagnostic agent, but also to increase the cancer targeting efficiency of a biotinylated anticancer agent.