Clostridial Neurotoxin Activation Loop for Precise Di-Chain Cleavage
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Solution Overview
Problem
Current methods for activating clostridial neurotoxins, such as botulinum neurotoxin serotype X (BoNT/X), using exogenous proteases like trypsin or Lys-C result in partial or improper cleavage, leading to the production of contaminating single-chain and/or inactive cleavage/degradation products, necessitating laborious purification processes.
Innovation Solution
Employing enterokinase and factor Xa proteases, which recognize and cleave the specific sequence Cys-(Xaa)a-Ile-Asp/Glu-Gly-Arg-(Yaa)b-Cys (SEQ ID NO: 1) in the activation loop of clostridial neurotoxins, allowing for efficient conversion of single-chain to di-chain toxins, thereby overcoming issues with existing proteases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional proteases (trypsin or Lys-C) are used to activate clostridial neurotoxins, then the activation process can be performed, but partial or improper cleavage occurs resulting in contaminating single-chain and inactive degradation products
Solution Approach 1:
The invention changes the protease selection parameter from conventional trypsin/Lys-C to enterokinase or factor Xa, which recognize and cleave at the specific IDGR or IEGR sequence in the activation loop. This parameter change resolves the contradiction by providing both high cleavage precision (specificity for the activation loop sequence) and high activation reliability (complete conversion to active di-chain toxin without degradation products)
Solution Approach 2:
The invention introduces a specific protease (enterokinase or factor Xa) as an intermediary that mediates the cleavage reaction. These proteases act as selective intermediaries that recognize the IDGR/IEGR sequence in the activation loop and perform cleavage without affecting other parts of the toxin molecule, thereby achieving both precision and reliability
2Adaptability or versatility
If multiple proteases are screened to find the correct activation protease for a new or modified neurotoxin, then activation can be achieved, but the process becomes time-consuming and complex
Solution Approach 1:
The invention establishes enterokinase and factor Xa as universal proteases for activating clostridial neurotoxins. By engineering the activation loop to contain IDGR or IEGR sequences, a single protease selection (enterokinase or factor Xa) can universally activate different neurotoxin variants without requiring screening, thus providing both versatility and time efficiency
Solution Approach 2:
The invention performs preliminary engineering of the activation loop sequence to contain the IDGR or IEGR recognition site before protease activation. This preliminary action ensures that the toxin is pre-configured for cleavage by enterokinase or factor Xa, eliminating the need for time-consuming protease screening during the activation phase
3Productivity
If BoNT/X is activated with trypsin or Lys-C, then the activation process proceeds, but complete degradation of the polypeptide occurs
Solution Approach 1:
The invention changes the protease parameter from trypsin/Lys-C to enterokinase or factor Xa, which have specific recognition sequences (IDGR/IEGR) located only in the activation loop. This parameter change ensures that cleavage occurs only at the intended site without degradation of the toxin polypeptide, maintaining both productivity and substance integrity
Solution Approach 2:
The invention converts the potential harm of protease-induced degradation into a benefit by using enterokinase or factor Xa, whose specific recognition of the IDGR/IEGR sequence ensures cleavage only at the activation loop. This transforms what could be a destructive process into a precise activation mechanism that preserves toxin integrity while achieving complete conversion to active form
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
This approach provides a universal activation method for clostridial neurotoxins, ensuring high substrate specificity and minimizing impurities, thus enhancing the production efficiency and purity of di-chain clostridial neurotoxins.
Implementation Method 1
enterokinase hydrolyses a peptide bond of the activation loop thereby producing a di-chain clostridial neurotoxin
Implementation Method 2
factor Xa hydrolyses a peptide bond of the activation loop thereby producing a di-chain clostridial neurotoxin
Data Source
AI summary
An engineered clostridial neurotoxin comprising an activation loop that comprises an amino acid sequence of the formula Cys-(Xaa)a-Ile-Asp/Glu-Gly-Arg-(Yaa)b-Cys(SEQ ID NO: 1), wherein a is an integer from 1 to 10, b is an integer from 4 to 15, each iteration of Xaa and Yaa individually represents an amino acid, and the engineered clostridial neurotoxin is not BoNT/C1, a method for producing the same, a method of treating a disease or condition comprising administering the engineered clostridial neurotoxin or the corresponding di-chain clostridial neurotoxin, a composition comprising the engineered clostridial neurotoxin or the corresponding di-chain clostridial neurotoxin, and a polynucleotide encoding the engineered clostridial neurotoxin. A method for proteolytically processing a single-chain clostridial neurotoxin into a corresponding di-chain clostridial neurotoxin, the method comprising contacting the single-chain clostridial neurotoxin with enterokinase or factor Xa and a di-chain clostridial neurotoxin produced using such a method. A method for hydrolyzing a peptide bond of a polypeptide comprising contacting the polypeptide with an enterokinase.