Environmental Dependence of the Structure of the C-terminal Domain of the SARS-CoV-2 Envelope Protein

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Abstract

The SARS-CoV-2 envelope protein (E) is involved in a broad spectrum of functions in the cycle of the virus, including assembly, budding, envelope formation, and pathogenesis. To enable these activities, E is likely to be capable of changing its conformation depending on environmental cues. To investigate this issue, here we characterised the structural properties of the C-terminal domain of E (E-CTD), which has been reported to interact with host cell membranes. We first studied the conformation of the E-CTD in solution, finding characteristic features of a disordered protein. By contrast, in the presence of large unilamellar vesicles and micelles, which mimic cell membranes, the E-CTD was observed to become structured. The E-CTD was also found to display conformational changes with osmolytes. Furthermore, prolonged incubation of the E-CTD under physiological conditions resulted in amyloid-like fibril formation. Taken together, these findings indicate that the E-CTD can change its conformation depending on its environment, ranging from a disordered state, to a membrane-bound folded state, and an amyloid state. Our results thus provide insight into the structural basis of the role of E in the viral infection process.

Highlights

  • The E-CTD of SARS-CoV-2 is intrinsically disordered in solution

  • The E-CTD folds into an ordered structure in presence of membrane mimetics

  • The E-CTD displays conformational changes in the presence of osmolytes

  • Prolonged incubation of the E-CTD leads to its self-assembly into amyloid-like fibrils

  • Graphical Abstract

    Structural heterogeneity of the E-CTD.

    The E-CTD shows a disordered secondary structure in an aqueous solution and converts into an ordered structure in the presence of membrane mimetics (neutral and negative lipids) and natural osmolytes (TMAO). Incubation at physiological condition shows typical amyloid-like fibrils. The yellow-colored structure represents a predicted structure of the E-CTD by PEP-FOLD.

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    1. SciScore for 10.1101/2020.12.29.424646: (What is this?)

      Please note, not all rigor criteria are appropriate for all manuscripts.

      Table 1: Rigor

      NIH rigor criteria are not applicable to paper type.

      Table 2: Resources

      Software and Algorithms
      SentencesResources
      To examine the conformational space accessible to the E-CTD, we performed all-atom MD simulations up to 1.5 μs using the Charmm36 force field [49] in Gromacs v5 [50], as reported previously [51].
      Gromacs
      suggested: (GROMACS, RRID:SCR_014565)

      Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).


      Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

      Results from TrialIdentifier: No clinical trial numbers were referenced.


      Results from Barzooka: We did not find any issues relating to the usage of bar graphs.


      Results from JetFighter: We did not find any issues relating to colormaps.


      Results from rtransparent:
      • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
      • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
      • No protocol registration statement was detected.

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