Splicing factor SF3B3, a NS5-binding protein, restricts ZIKV infection by targeting GCH1

Virol Sin. 2023 Apr;38(2):222-232. doi: 10.1016/j.virs.2022.12.005. Epub 2022 Dec 23.

Abstract

Zika virus (ZIKV), a positive-sense single-stranded RNA virus, causes congenital ZIKV syndrome in children and Guillain-Barré Syndrome (GBS) in adults. ZIKV expresses nonstructural protein 5 (NS5), a large protein that is essential for viral replication. ZIKV NS5 confers the ability to evade interferon (IFN) signalling; however, the exact mechanism remains unclear. In this study, we employed affinity pull-down and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses and found that splicing factor 3b subunit 3 (SF3B3) is associated with the NS5-Flag pull-down complex through interaction with NS5. Functional assays showed that SF3B3 overexpression inhibited ZIKV replication by promoting IFN-stimulated gene (ISG) expression whereas silencing of SF3B3 inhibited expression of ISGs to promote ZIKV replication. GTP cyclohydrolase I (GCH1) is the first and rate-limiting enzyme in tetrahydrobiopterin (BH4) biosynthesis. NS5 upregulates the expression of GCH1 during ZIKV infection. And GCH1 marginally promoted ZIKV replication via the IFN pathway. Additionally, GCH1 expression is related to the regulation of SF3B3. Overexpression of the SF3B3 protein effectively reduced GCH1 protein levels, whereas SF3B3 knockdown increased its levels. These findings indicated that ZIKV NS5 binding protein SF3B3 contributed to the host immune response against ZIKV replication by modulating the expression of GCH1.

Keywords: GTP cyclohydrolase I (GCH1); IFN signalling Pathway; IFN-stimulated gene (ISGs); Nonstructural protein 5 (NS5); Splicing factor 3b subunit 3 (SF3B3).

MeSH terms

  • Carrier Proteins / metabolism
  • Carrier Proteins / pharmacology
  • Child
  • Chromatography, Liquid
  • GTP Cyclohydrolase / metabolism
  • Humans
  • Protein Binding
  • RNA Splicing Factors / metabolism
  • Tandem Mass Spectrometry
  • Viral Nonstructural Proteins / genetics
  • Zika Virus Infection*
  • Zika Virus*

Substances

  • Carrier Proteins
  • RNA Splicing Factors
  • SF3B3 protein, human
  • Viral Nonstructural Proteins
  • GTP Cyclohydrolase