Engineered AID Mutants for Controlled Somatic Hypermutation
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Solution Overview
Problem
Current somatic hypermutation systems face challenges in targeting mutations to specific genes, achieving high mutation rates, and controlling hypermutation, particularly in non-B cell lines, with limitations in efficiency and stability, and difficulties in regulating mutagenesis after desired phenotypes are selected.
Innovation Solution
Development of a functional mutant activation-induced cytidine deaminase (AID) protein with specific amino acid substitutions, such as at residues 34, 82, and 156, which enhances activity by at least 10-fold in bacterial papillation assays, and use of expression vectors to induce mutations in cells, allowing for controlled and efficient somatic hypermutation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If native antibodies are isolated from human or animal immune systems, then the antibodies are immunogenically tolerated and highly expressed in mammalian cells, but the affinity is limited to about 100 pM due to intrinsic affinity ceiling
Solution Approach 1:
The patent applies preliminary action by first isolating native antibodies that are immunogenically tolerated, then subjecting them to in vitro somatic hypermutation using engineered AID proteins to evolve higher affinity variants. This two-stage approach allows the antibody to first ensure compatibility with mammalian systems, then optimize binding affinity through controlled mutagenesis and selection processes.
2Measurement precision
If phage display libraries are used to generate high affinity antibodies, then the affinity can exceed 100 pM, but the library size is limited and cannot explore the full immune repertoire
Solution Approach 1:
The patent merges the advantages of both approaches by combining the immunogenic tolerance and high expression capability of native antibodies with the high affinity potential of phage display. This is achieved by using in vitro somatic hypermutation on native antibodies, which allows exploration of a much larger sequence space than phage libraries while maintaining mammalian compatibility.
3Adaptability or versatility
If random mutagenesis is used in combination with phage display, then antibody diversity is generated, but selectivity profiling is lost resulting in human anti-human immunity issues and undesirable cross reactivity
Solution Approach 1:
The patent implements feedback control by using engineered AID proteins that can be regulated in expression and activity. The somatic hypermutation process is controlled through regulated AID expression, allowing iterative cycles of mutagenesis followed by selection for desired properties such as affinity, specificity, and lack of cross-reactivity. This feedback loop ensures that diversity is generated while maintaining selectivity.
4Reliability
If B cell lines like Ramos are used for in vitro somatic hypermutation, then hypermutation can occur, but the cell division rate is slow and transfection efficiency is low
Solution Approach 1:
The patent applies local quality by introducing engineered AID proteins into non-B cell lines that have been specifically optimized for high transfection efficiency and rapid growth. The hypermutation capability is localized to the introduced AID protein rather than relying on the endogenous properties of B cell lines, allowing the use of more productive host cells.
5Productivity
If constitutive hypermutation is achieved in B cell lines, then mutation occurs continuously, but the process cannot be controlled or switched off after desired phenotypes are selected
Solution Approach 1:
The patent implements dynamics by using engineered AID proteins with regulated expression systems that allow the mutation rate to be dynamically adjusted. The AID protein expression can be induced or repressed as needed, enabling control over when mutagenesis occurs. This allows high mutation rates during the evolution phase, then complete shutdown once desired phenotypes are achieved.
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 enhanced AID protein improves the efficiency and control of somatic hypermutation, enabling targeted and stable mutation of specific genes, overcoming previous limitations in mutation rates and stability, and facilitating the selection of desired phenotypes.
Implementation Method 1
activation-induced cytidine deaminase (AID) protein whose amino acid sequence differs from the amino acid sequence of a human AID protein
Data Source
AI summary
The invention provides functional mutants of activation-induced cytidine deaminase (AID) protein that have increased activity as compared to a wild-type AID protein. The invention also provides nucleic acids encoding the functional AID mutants, and vectors and cells comprising the nucleic acids. The invention further provides methods of using the functional mutant AID proteins.