secA Promoter for Moderate Transgene Expression
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Solution Overview
Problem
There is a constant need for novel promoter sequences that can drive moderate expression levels of transgenes in host cells, particularly for products like restriction modification system components and antibiotic resistance proteins, as existing promoters often fail to provide optimal expression levels without toxicity to the host cell.
Innovation Solution
A nucleic acid construct comprising a promoter sequence of an operon comprising a secA gene or a functional fragment/variant thereof, which is heterologous to the polynucleotide, is used to drive the expression of polynucleotides in host cells, providing a moderate expression level and avoiding toxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If strong promoters are used to drive high expression levels of transgenes, then protein production is improved, but host cell toxicity increases and continuous cultivation becomes impossible
Solution Approach 1:
The patent changes the parameter of promoter strength by selecting and characterizing specific promoter sequences from the secA operon that provide moderate expression levels. This parameter change allows the host cell to tolerate the transgene product while maintaining continuous cultivation capability, resolving the contradiction between high protein production and host cell toxicity.
2Productivity
If existing promoters are used for transgene expression, then expression is achieved, but optimal moderate expression levels cannot be obtained without toxicity
Solution Approach 1:
The patent creates new promoter sequences by copying and adapting the secA operon promoter structure to drive transgene expression. These copied promoter sequences provide optimal moderate expression levels that enable continuous cultivation, improving both productivity and reliability simultaneously.
Data Source
AI summary
The present invention is directed to a nucleic acid construct comprising a polynucleotide operably linked to one or more control sequence that directs the expression of the polynucleotide in a host cell, wherein at least one control sequence comprises a promoter sequence of an operon comprising a secA gene or a functional fragment or functional variant thereof and wherein said promoter sequence is heterologous to the polynucleotide. In a further embodiment, the invention is directed to an expression vector and a host cell comprising the nucleic acid construct comprising the promoter sequence described herein and a method of expressing a polynucleotide in a host cell.