Mutated ALAS Constructs for Higher Heme-Protein Expression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing heme-binding proteins in yeast cells, such as Pichia pastoris, are limited by the rate of heme biosynthesis, which is constrained by the translocation of aminolevulinic acid synthase (ALAS) proteins to mitochondria due to heme regulatory motifs (HRMs), leading to inefficient expression of these proteins.
Innovation Solution
Introduction of mutations in the HRMs of ALAS proteins, specifically cysteine to serine mutations in both HRMs, enhances the translocation of ALAS to mitochondria, allowing for increased expression of heme-binding proteins when co-expressed with exogenous nucleic acid constructs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wild-type ALAS proteins with intact heme responsive motifs (HRMs) are used, then the cell maintains proper heme regulation and mitochondrial translocation control, but the expression level of heme-binding proteins remains limited due to constrained ALAS translocation
Solution Approach 1:
The invention applies local quality by making specific mutations only in the heme responsive motifs (HRMs) of the ALAS protein while leaving the rest of the protein structure intact. The cysteine residues at specific positions within the HRMs are mutated to serine or alanine, creating localized changes that enhance mitochondrial translocation without disrupting the overall protein function or other regulatory mechanisms
Solution Approach 2:
The invention changes the chemical parameters of the ALAS protein by mutating cysteine residues to serine or alanine in the HRMs. This parameter change alters the protein's interaction with heme and its translocation properties, enabling increased productivity while maintaining sufficient regulatory control through the modified but still functional HRMs
2Productivity
If mutations in HRMs (cysteine to serine) are introduced in ALAS proteins, then translocation to mitochondria is enhanced and expression of heme-binding proteins increases by 5-20%, but the heme regulatory control may be compromised
Solution Approach 1:
The invention applies partial action by mutating only specific cysteine residues within the HRMs rather than eliminating the entire regulatory function. The mutations are targeted at specific positions (e.g., Cys-12, Cys-39) to achieve sufficient enhancement in translocation (5-20% increase in titer) while preserving enough HRM functionality to maintain basic heme regulatory control
Solution Approach 2:
The invention changes the physical-chemical parameters of the HRMs by substituting cysteine with serine or alanine. This parameter change modifies the heme-binding properties and translocation efficiency of ALAS, achieving the desired balance between enhanced productivity and maintained regulatory reliability
Data Source
AI summary
This document relates to materials and methods for the production of protein. In one aspect, this document provides a first exogenous nucleic acid construct including a nucleotide sequence encoding an aminolevulinate synthase (ALAS) protein operably linked to a first promoter element, wherein the ALAS includes at least a first heme responsive motif (HRM), and wherein the ALAS includes a mutation in the first HRM, and a second exogenous nucleic acid construct comprising a nucleotide sequence encoding a heme-binding protein, wherein the second exogenous nucleic acid construct including a nucleotide sequence encoding the heme-binding protein is operably linked to the first promoter element or is operably linked to a second promoter element.