Modified Defensin Peptides for Cation-Tolerant Antimicrobial Activity

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Solution Overview

Problem

Existing plant defensins lose antifungal activity at elevated concentrations of mono- and bivalent cations, limiting their effectiveness in transgenic crops and vertebrate applications.

Innovation Solution

Development of modified defensin peptides with enhanced cation tolerance and hydrophobicity, maintaining antimicrobial activity in the presence of physiological cations, and incorporating recombinant polynucleotides for genetic modification in plants and animals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If plant defensins are used to control plant pathogens, then antimicrobial activity is achieved, but activity is lost in the presence of elevated cation concentrations

Engineering Contradiction:

Improveantimicrobial activityVSAvoidcation tolerance

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by systematically modifying amino acid residues in the defensin peptide sequence, particularly at positions 6, 7, 8, 11, 12, and 13. These modifications alter the peptide's charge distribution and hydrophobicity, enabling it to maintain antimicrobial activity in high cation environments while preserving its ability to interact with microbial membranes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite-like structures by combining conserved cysteine residues (which form disulfide bonds for structural stability) with modified amino acid sequences that provide cation tolerance. The resulting hybrid peptide structure integrates both stability and environmental adaptability features.

Inventive Principle:

Principle #40Composite materials

2Reliability

If defensin peptides are modified to increase cation tolerance, then activity in physiological conditions is improved, but sequence complexity increases

Engineering Contradiction:

Improveactivity in cation-rich environmentsVSAvoidpeptide sequence complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by making targeted modifications at specific positions (6, 7, 8, 11, 12, 13) rather than throughout the entire sequence. Each modification is strategically placed to address cation tolerance while preserving the overall simplicity and conserved structural features of the defensin peptide.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If full-length defensin proteins are used, then broad antimicrobial spectrum is achieved, but expression in transgenic plants shows reduced effectiveness

Engineering Contradiction:

Improveantimicrobial spectrumVSAvoideffectiveness in transgenic crops

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent extracts the essential antimicrobial domain from full-length defensin proteins by using truncated peptide sequences (15-30 amino acids) that contain the critical functional regions. This extraction removes unnecessary portions that may hinder expression or stability in transgenic systems while retaining broad-spectrum activity.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12433296B2Modified antimicrobial peptides

Publication Date: 2025.10.07 DONALD DANFORTH PLANT SCI CENT

AI summary

Antimicrobial defensin peptide variants comprising modified C-terminal fragments of a defensin and nucleic acids encoding the same are disclosed. Compositions comprising the defensin variant peptides and methods of their use to control microbial infections of plants and vertebrate subjects as well as contamination of feedstuffs and foodstuffs are also disclosed.