Type III-D CRISPR Detection Using Cyclic Oligoadenylate Signaling
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Solution Overview
Problem
There is a lack of detailed structural knowledge and proven functions for Type III-D CRISPR-Cas systems, particularly the Type III-Dv system, limiting their application in real-world scenarios.
Innovation Solution
A method involving a Type III-D CRISPR-Cas system comprising specific subunits (Cas7-Cas5-Cas11 fusion, Cas7-Cas7 fusion, Cas7-insertion, Cas10, and Csx19) is used to modify or detect single-stranded nucleic acids, utilizing guide RNA for target recognition and cyclic oligoadenylate production to activate nucleases for cleavage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Type III-D CRISPR-Cas systems are used for target recognition and nucleic acid modification, then functional capability is achieved, but lack of structural knowledge limits application
Solution Approach 1:
The patent uses guide RNA as an intermediary component that bridges the gap between the Type III-D CRISPR-Cas system and target nucleic acids. The guide RNA contains a recognition sequence that hybridizes to the target, enabling the system to achieve functional capability despite incomplete structural knowledge of the Cas proteins themselves.
2Reliability
If multiple fusion subunits are used in Type III-Dv system, then nuclease activity is enhanced, but system complexity increases
Solution Approach 1:
The patent combines multiple Cas protein functions into fusion subunits (Cas7-Cas5-Cas11, Cas7-Cas7, Cas7-insertion). These fusion proteins integrate nuclease domains, RNA binding domains, and cyclic oligoadenylate synthesis capabilities into single polypeptides, enhancing nuclease activity while managing system complexity through functional integration rather than separate components.
Solution Approach 2:
The fusion subunits in the Type III-Dv system perform multiple functions simultaneously - the Cas7 domains provide nuclease activity, Cas5 domains facilitate crRNA binding, and Cas11 domains contribute to cyclic oligoadenylate production. This multi-functionality allows a single protein complex to execute the complete CRISPR interference pathway.
3Measurement precision
If cyclic oligoadenylate production is activated for nuclease activation, then detection capability is improved, but energy consumption increases
Solution Approach 1:
The Type III-D CRISPR-Cas system employs a feedback mechanism where target nucleic acid binding triggers cyclic oligoadenylate production, which in turn activates accessory nucleases for collateral cleavage. This feedback loop ensures that energy-consuming nuclease activation only occurs when the target is actually detected, optimizing detection capability while minimizing unnecessary energy consumption.
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 method enables effective modification and detection of target nucleic acids, providing a functional basis for potential applications in biotechnology and biotechnological defense mechanisms.
Implementation Method 1
a guide RNA which is complementary to a recognition sequence in the target single-stranded nucleic acid
Implementation Method 2
the ability to produce secondary messenger molecules (cyclic oligoadenylates) via Cas10
Implementation Method 3
Accessory proteins are activated upon binding these cyclic oligoadenylates and can function to cleave RNA, DNA or proteins
Data Source
AI summary
The present invention is concerned with novel CRISPR-Cas systems which are configured to detect the presence of a target nucleic acid in a sample through activation of secondary nucleases which bind and cleave a nucleic acid probe modified with a (e.g.) fluorophore/quencher moieties, where a change in the property of the probe (e.g. modified fluorescence) reflects the presence of the target nucleic acid in a sample to be tested.