title: RPLP1 and RPLP2 Are Essential Flavivirus Host Factors That Promote Early Viral Protein Accumulation.
abstract: The Flavivirus genus contains several arthropod-borne viruses that pose global health threats, including dengue viruses (DENV), yellow fever virus (YFV), and Zika virus (ZIKV). In order to understand how these viruses replicate in human cells, we previously conducted genome-scale RNA interference screens to identify candidate host factors. In these screens, we identified ribosomal proteins RPLP1 and RPLP2 (RPLP1/2) to be among the most crucial putative host factors required for DENV and YFV infection. RPLP1/2 are phosphoproteins that bind the ribosome through interaction with another ribosomal protein, RPLP0, to form a structure termed the ribosomal stalk. RPLP1/2 were validated as essential host factors for DENV, YFV, and ZIKV infection in two human cell lines: A549 lung adenocarcinoma and HuH-7 hepatoma cells, and for productive DENV infection of Aedes aegypti mosquitoes. Depletion of RPLP1/2 caused moderate cell-line-specific effects on global protein synthesis, as determined by metabolic labeling. In A549 cells, global translation was increased, while in HuH-7 cells it was reduced, albeit both of these effects were modest. In contrast, RPLP1/2 knockdown strongly reduced early DENV protein accumulation, suggesting a requirement for RPLP1/2 in viral translation. Furthermore, knockdown of RPLP1/2 reduced levels of DENV structural proteins expressed from an exogenous transgene. We postulate that these ribosomal proteins are required for efficient translation elongation through the viral open reading frame. In summary, this work identifies RPLP1/2 as critical flaviviral host factors required for translation.
  
  
  
  Flaviviruses cause important diseases in humans. Examples of mosquito-transmitted flaviviruses include dengue, yellow fever and Zika viruses. Viruses require a plethora of cellular factors to infect cells, and the ribosome plays an essential role in all viral infections. The ribosome is a complex macromolecular machine composed of RNA and proteins and it is responsible for protein synthesis. We identified two specific ribosomal proteins that are strictly required for flavivirus infection of human cells and mosquitoes: RPLP1 and RPLP2 (RPLP1/2). These proteins are part of a structure known as the ribosomal stalk and help orchestrate the elongation phase of translation. We show that flaviviruses are particularly dependent on the function of RPLP1/2. Our findings suggest that ribosome composition is an important factor for virus translation and may represent a regulatory layer for translation of specific cellular mRNAs.
authors.affiliation: Department of Molecular Genetics and Microbiology, Center for RNA Biology, Duke University, Durham, North Carolina, USA.|Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Rafael K
authors.initials: RK
authors.lastname: Campos
authors.affiliation: Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Wong
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Xuping
authors.identifier: http://orcid.org/0000-0003-0918-016X
authors.initials: X
authors.lastname: Xie
authors.affiliation: Department of Molecular Genetics and Microbiology, Center for RNA Biology, Duke University, Durham, North Carolina, USA.
authors.forename: Yi-Fan
authors.initials: YF
authors.lastname: Lu
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA.|Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore.|Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, USA.|Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Pei-Yong
authors.initials: PY
authors.lastname: Shi
authors.affiliation: Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore.|MIVEGEC, IRD, Montpellier, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Pompon
authors.affiliation: Department of Molecular Genetics and Microbiology, Center for RNA Biology, Duke University, Durham, North Carolina, USA maragarc@utmb.edu ssbradri@utmb.edu.|Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA.|Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore.
authors.forename: Mariano A
authors.initials: MA
authors.lastname: Garcia-Blanco
authors.affiliation: Department of Molecular Genetics and Microbiology, Center for RNA Biology, Duke University, Durham, North Carolina, USA maragarc@utmb.edu ssbradri@utmb.edu.|Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Shelton S
authors.initials: SS
authors.lastname: Bradrick
mesh_terms: D000330:Aedes / Q000821:virology; D000818:Animals; D002460:Cell Line; D003716:Dengue Virus / Q000502:physiology; D005416:Flavivirus / Q000502:physiology*; D018177:Flavivirus Infections / Q000235:genetics / Q000378:metabolism* / Q000821:virology*; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D054884:Host-Pathogen Interactions; D006801:Humans; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication; D015005:Yellow fever virus / Q000502:physiology
chemical_list: D010750:Phosphoproteins; D012269:Ribosomal Proteins; D014764:Viral Proteins; C031937:phosphoprotein P2, ribosomal; C035690:ribosomal phosphoprotein P1
keywords: flavivirus; ribosomal proteins; translation