LONRF2 Polypeptide Binding for Misfolded Protein Detection and Reduction

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Solution Overview

Problem

Current technologies lack effective methods to identify and eliminate structurally abnormal proteins, particularly in mammals, which are associated with neurodegenerative diseases like ALS, as key nuclear PQC ubiquitin ligases have not been identified.

Innovation Solution

The use of LONRF2, a member of the LONRF family of ubiquitin ligases, which binds to and ubiquitinates structurally abnormal proteins, is employed to develop agents for detection and reduction of these proteins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If nuclear PQC ubiquitin ligases are identified and used to destroy structurally abnormal proteins, then protein quality control is improved, but the complexity of the system increases due to lack of characterized ligases in mammals

Engineering Contradiction:

Improveprotein quality controlVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces LONRF2 as an intermediary protein that mediates between structurally abnormal proteins and the ubiquitin degradation system. LONRF2 binds to misfolded proteins through its LonSB domain and facilitates their ubiquitination and degradation, serving as a key mediator in nuclear PQC that was previously uncharacterized in mammals.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses the bacterial Lon protease LonSB domain as a functional template to identify and characterize the mammalian LONRF2 protein. By comparing sequence homology and functional characteristics between bacterial and mammalian systems, the patent successfully copied the functional mechanism of bacterial PQC into the mammalian nuclear system.

Inventive Principle:

Principle #26Copying

2Measurement precision

If specific binding sites for structurally abnormal proteins are developed, then detection precision is improved, but the difficulty of detecting and measuring increases due to lack of specific markers

Engineering Contradiction:

Improvedetection precisionVSAvoiddetection difficulty

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent extracts the specific binding function from the complex LONRF2 protein by isolating and characterizing the LonSB domain (amino acid sequence SEQ ID NO: 2) as the critical functional region. This extracted domain specifically binds to structurally abnormal proteins through conformational recognition, providing a precise detection target that simplifies measurement while maintaining high specificity.

Inventive Principle:

Principle #2Taking out (Extraction)

3Quantity of substance

If ubiquitin ligases are used to reduce structurally abnormal proteins, then protein accumulation is reduced, but the loss of substance increases due to degradation of abnormal proteins

Engineering Contradiction:

Improveprotein accumulationVSAvoidprotein degradation

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

The patent converts the harmful accumulation of structurally abnormal proteins into a beneficial process by utilizing LONRF2-mediated ubiquitination. The abnormal proteins, which would normally accumulate and cause neurodegenerative diseases, are transformed into a controlled degradation pathway that eliminates them through the ubiquitin-proteasome system, turning a harmful state into a protective mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 LONRF2-based agents effectively detect and reduce structurally abnormal proteins, offering potential treatments for neurodegenerative diseases by preventing protein accumulation and improving functional decline.

Implementation Method 1

The LonSB domain is a conformational recognition domain that does not recognize a folded protein but recognizes a misfolded protein

Methodology Applied

Scientific EffectConformational recognition:

Implementation Method 2

LONRF2, a member of the LONRF family of ubiquitin ligases, is a PQC ubiquitin ligase that binds to and ubiquitinates structurally abnormal proteins

Methodology Applied

Scientific EffectUbiquitination:

Implementation Method 3

protein degradation via the proteasome or autophagy

Methodology Applied

Scientific EffectProteolytic degradation: Decomposition (biological)

Data Source

PatentUS20260043817A1Agent for detecting structurally abnormal protein and agent for reducing structurally abnormal protein

Publication Date: 2026.02.12 THE UNIV OF TOKYO

AI summary

The present invention provides a polypeptide that specifically recognizes structurally abnormal proteins generated in mammals due to misfolding or the like, and an agent for detecting or reducing structurally abnormal proteins that uses the polypeptide. The present invention relates to an agent for detecting structurally abnormal proteins, comprising as an active ingredient a polypeptide having structurally abnormal proteins-binding site which is a polypeptide consisting of the amino acid sequence represented by SEQ ID NO:2, or a polypeptide consisting of an amino acid sequence having 90% or more sequence identity with the amino acid sequence and having binding activity to structurally abnormal proteins, and an agent for reducing structurally abnormal proteins comprising as an active ingredient a polypeptide containing the structurally abnormal protein binding site and a ubiquitin ligase active site.