Optimization of 5′UTR to evade SARS-CoV-2 Nonstructural protein 1-directed inhibition of protein synthesis in cells

Shih Cheng Chen, Cui Ting Xu, Chuan Fu Chang, Ting Yu Chao, Chia Chi Lin, Pei Wen Fu, Chien Hung Yu

Research output: Contribution to journalArticlepeer-review


Abstract: Maximizing the expression level of therapeutic proteins in cells is the general goal for DNA/mRNA therapies. It is particularly challenging to achieve efficient protein expression in the cellular contexts with inhibited translation machineries, such as in the presence of cellular Nonstructural protein 1 (Nsp1) of coronaviruses (CoVs) that has been reported to inhibit overall protein synthesis of host genes and exogenously delivered mRNAs/DNAs. In this study, we thoroughly examined the sequence and structure contexts of viral and non-viral 5′UTRs that determine the protein expression levels of exogenously delivered DNAs and mRNAs in cells expressing SARS-CoV-2 Nsp1. It was found that high 5′-proximal A/U content promotes an escape from Nsp1-directed inhibition of protein synthesis and results in selective protein expression. Furthermore, 5′-proximal Cs were found to significantly enhance the protein expression in an Nsp1-dependent manner, while Gs located at a specific window close to the 5′-end counteract such enhancement. The distinct protein expression levels resulted from different 5′UTRs were found correlated to Nsp1-induced mRNA degradations. These findings ultimately enabled rational designs for optimized 5′UTRs that lead to strong expression of exogenous proteins regardless of the translationally repressive Nsp1. On the other hand, we have also identified several 5′-proximal sequences derived from host genes that are capable of mediating the escapes. These results provided novel perspectives to the optimizations of 5′UTRs for DNA/mRNA therapies and/or vaccinations, as well as shedding light on the potential host escapees from Nsp1-directed translational shutoffs. Key points: • The 5′-proximal SL1 and 5a/b derived from SARS-CoV-2 genomic RNA promote exogenous protein synthesis in cells expressing Nsp1 comparing with non-specific 5′UTRs. • Specific 5′-proximal sequence contexts are the key determinants of the escapes from Nsp1-directed translational repression and thereby enhance protein expressions. • Systematic mutagenesis identified optimized 5′UTRs that strongly enhance protein expression and promote resistance to Nsp1-induced translational repression and RNA degradation.

Original languageEnglish
Pages (from-to)2451-2468
Number of pages18
JournalApplied Microbiology and Biotechnology
Issue number7-8
Publication statusPublished - 2023 Apr

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Applied Microbiology and Biotechnology


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