Site-Specific O-Sulfotyrosine Incorporation for Homogeneous Protein Sulfation

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Solution Overview

Problem

Existing methods struggle to express recombinant proteins in eukaryotic hosts with homogeneous tyrosine sulfation, as endogenous sulfotransferases cannot keep up with high expression levels, leading to heterogeneous modification of tyrosine residues, making it difficult to study the roles of individual sulfations.

Innovation Solution

Development of an engineered tyrosyl RNA synthetase/tRNA pair in Escherichia coli and mammalian cells that co-translationally incorporates tyrosine analogs, specifically O-sulfotyrosine, in response to UAG codons, enabling site-specific sulfation of proteins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If proteins are overexpressed in eukaryotic hosts, then productivity increases, but the endogenous sulfotransferases cannot keep up with high expression levels, leading to heterogeneous modification of tyrosine residues

Engineering Contradiction:

Improveprotein expression levelVSAvoidsulfation homogeneity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent introduces an engineered tyrosyl-tRNA synthetase as an intermediary enzyme that directly charges tRNA with O-sulfotyrosine, bypassing the rate-limiting step of endogenous TPST sulfotransferases. This intermediary system decouples protein expression rate from sulfation rate, allowing both high productivity and homogeneous modification.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The engineered tyrosyl-tRNA synthetase enables the translation machinery itself to incorporate sulfated tyrosine during co-translational synthesis. The system uses the cell's own translation apparatus to achieve homogeneous sulfation, turning the translation process into a self-servicing modification system rather than relying on separate post-translational sulfotransferase activity.

Inventive Principle:

Principle #25Self-service

2Adaptability or versatility

If multiple distinct sulfation sites are present in a protein, then the protein's functional complexity increases, but it is not possible to homogenously modify a subset of these sites

Engineering Contradiction:

Improvesulfation site diversityVSAvoidsite-specific modification control

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent employs site-specific incorporation of O-sulfotyrosine by placing UAG stop codons at specific positions in the protein coding sequence. This allows different regions of the same protein to have different modification states (sulfated vs. non-sulfated), enabling local quality control and precise investigation of individual sulfation site functions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The protein sequence is segmented into regions with UAG codons and regions with standard codons, allowing independent control of sulfation at different sites. This segmentation strategy enables the creation of protein variants with selective sulfation patterns to study the function of specific sulfation sites.

Inventive Principle:

Principle #1Segmentation

3Reliability

If endogenous sulfotransferases are used for protein sulfation, then the modification occurs naturally, but the enzymes cannot keep up with high expression levels, leading to incomplete sulfation

Engineering Contradiction:

Improvenatural modification fidelityVSAvoidsulfation rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the kinetic parameters of the sulfation system by using an engineered tyrosyl-tRNA synthetase with high catalytic efficiency for O-sulfotyrosine. This engineered enzyme has parameters optimized for rapid sulfation that can match or exceed high protein expression rates, overcoming the rate limitation of endogenous TPST enzymes while maintaining modification fidelity.

Inventive Principle:

Principle #35Parameter changes

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

Enables the expression of eukaryotic proteins with precise sulfation, allowing for the study of sulfation's consequences and the development of sulfated antibodies with enhanced pathogen targeting.

Implementation Method 1

an engineered tyrosyl RNA synthetase/tRNA pair that co-translationally incorporates tyrosine analogs, specifically O-sulfotyrosine

Methodology Applied

Scientific EffectAminoacylation: Chemical Bonding

Implementation Method 2

co-translationally incorporates tyrosine analogs, specifically O-sulfotyrosine, in response to UAG codons

Methodology Applied

Scientific EffectCo-translational incorporation:

Data Source

PatentUS20260055391A1Genetically Encoded Tyrosine Sulfation of Proteins in Eukaryotes

Publication Date: 2026.02.26 BOSTON COLLEGE

AI summary

An engineered tyrosyl-tRNA synthetase/tRNA pair that co-translationally incorporates O-sulfotyrosine in response to UAG codons in E. coli and mammalian cells is described herein. This platform enables recombinant expression of eukaryotic proteins homogeneously sulfated at chosen sites.