EqFP578 Mutants for Red Fluorescence and Reduced Aggregation
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Solution Overview
Problem
Current fluorescent proteins, such as GFP, have limitations in terms of spectral diversity and suitability for various research applications, necessitating the development of novel fluorescent proteins with improved properties.
Innovation Solution
The isolation and genetic engineering of nucleic acid molecules encoding the Entacmaea quadricolor fluorescent protein EqFP578 and its mutants, which offer enhanced folding, reduced aggregation and oligomerization, and altered spectral characteristics, are provided. These mutants include specific amino acid substitutions that improve protein stability and fluorescence intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If GFP and its mutants are used as fluorescent markers, then fluorescence intensity is achieved, but spectral diversity is limited
Solution Approach 1:
The patent applies parameter changes by systematically modifying amino acid residues at positions 65, 148, and 203 to generate fluorescent proteins with different spectral properties. Specific substitutions (e.g., S65T, Y148F, H203Y) shift excitation and emission wavelengths, creating cyan, green, yellow, and red fluorescent variants from a single ancestral GFP sequence, thus achieving spectral diversity while maintaining fluorescence intensity
Solution Approach 2:
The patent applies local quality by making targeted amino acid substitutions at specific positions within the GFP sequence rather than random mutations. Each position (65, 148, 203) is specifically modified to control different aspects of fluorescence: position 65 affects quantum yield and excitation wavelength, position 148 influences emission wavelength and photostability, and position 203 controls spectral shape and brightness, allowing precise control over fluorescent properties
2Illumination intensity
If wild-type EqFP578 is expressed, then red fluorescence is achieved, but aggregation and oligomerization occur
Solution Approach 1:
The patent applies the taking out principle by removing problematic amino acid residues from the wild-type EqFP578 sequence that promote aggregation and oligomerization. Specific residues involved in intermolecular interactions are eliminated or replaced, extracting the aggregation-prone properties while retaining the red fluorescent chromophore functionality, resulting in monomeric fluorescent proteins suitable for imaging applications
Solution Approach 2:
The patent applies this principle by creating simplified, engineered versions of EqFP578 that sacrifice some native structural features responsible for aggregation but gain improved solubility and monomeric behavior. The engineered variants use reduced amino acid sequences or modified terminal regions that prevent oligomerization while maintaining sufficient fluorescence for practical use, effectively replacing the problematic wild-type protein
3Ease of operation
If traditional GFP variants are used, then green fluorescence is achieved, but suitability for multi-color imaging is reduced
Solution Approach 1:
The patent applies universality by developing a family of fluorescent proteins from a single GFP ancestor that can perform multiple spectral functions. By systematically varying amino acid substitutions at key positions, the invention creates cyan, green, yellow, and red fluorescent variants that can be used individually or in combination for multi-color imaging, allowing a single genetic construct system to achieve versatile spectral applications
Solution Approach 2:
The patent applies segmentation by dividing the spectral range into distinct segments (cyan, green, yellow, red) achieved through specific amino acid substitutions. Each substitution combination creates a fluorescent protein optimized for a particular spectral segment, allowing researchers to select and combine specific variants for multi-color imaging experiments, effectively segmenting the fluorescence spectrum into usable modules
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 engineered fluorescent proteins exhibit improved folding, faster chromophore maturation, reduced aggregation, and altered spectral properties, making them suitable for advanced biological imaging and research applications.
Implementation Method 1
Fluorescent proteins are proteins that exhibit fluorescence upon irradiation with light of the appropriate excitation wavelength
Data Source
AI summary
The present invention provides nucleic acid molecules encoding novel red fluorescent proteins from Entacmaea quadricolor and mutants thereof. Also of interest are proteins that are substantially similar to the novel red fluorescent proteins. In addition, host cells, stable cell lines and transgenic organisms comprising the nucleic acid molecules encoding the novel red fluorescent proteins are provided. The subject proteins and nucleic acid compositions find use in a variety of different applications and methods, particularly for labeling of biomolecules, cells, or cell organelles. Finally, kits for use in such methods and applications are provided.