Genetically Encoded Fluorescent Sensors for SARS-CoV-2 Papain-like Protease PLpro

Elena L. Sokolinskaya, Lidia V. Putlyaeva, Vasilisa S. Polinovskaya, Konstantin A. Lukyanov

Research output: Contribution to journalArticlepeer-review

Abstract

In the SARS-CoV-2 lifecycle, papain-like protease PLpro cuts off the non-structural proteins nsp1, nsp2, and nsp3 from a large polyprotein. This is the earliest viral enzymatic activity, which is crucial for all downstream steps. Here, we designed two genetically encoded fluorescent sensors for the real-time detection of PLpro activity in live cells. The first sensor was based on the Förster resonance energy transfer (FRET) between the red fluorescent protein mScarlet as a donor and the biliverdin-binding near-infrared fluorescent protein miRFP670 as an acceptor. A linker with the PLpro recognition site LKGG in between made this FRET pair sensitive to PLpro cleavage. Upon the co-expression of mScarlet-LKGG-miRFP670 and PLpro in HeLa cells, we observed a gradual increase in the donor fluorescence intensity of about 1.5-fold. In the second sensor, both PLpro and its target—green mNeonGreen and red mScarletI fluorescent proteins separated by an LKGG-containing linker—were attached to the endoplasmic reticulum (ER) membrane. Upon cleavage by PLpro, mScarletI diffused from the ER throughout the cell. About a two-fold increase in the nucleus/cytoplasm ratio was observed as a result of the PLpro action. We believe that the new PLpro sensors can potentially be used to detect the earliest stages of SARS-CoV-2 propagation in live cells as well as for the screening of PLpro inhibitors.

Original languageEnglish
Article number7826
JournalInternational Journal of Molecular Sciences
Volume23
Issue number14
DOIs
Publication statusPublished - Jul 2022

Keywords

  • coronavirus
  • COVID-19
  • FRET
  • genetically encoded probes
  • live cell imaging
  • protease PLpro
  • SARS-CoV-2
  • translocation

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