title: New World and Old World Alphaviruses Have Evolved to Exploit Different Components of Stress Granules, FXR and G3BP Proteins, for Assembly of Viral Replication Complexes.
abstract: The positive-strand RNA viruses initiate their amplification in the cell from a single genome delivered by virion. This single RNA molecule needs to become involved in replication process before it is recognized and degraded by cellular machinery. In this study, we show that distantly related New World and Old World alphaviruses have independently evolved to utilize different cellular stress granule-related proteins for assembly of complexes, which recruit viral genomic RNA and facilitate formation of viral replication complexes (vRCs). Venezuelan equine encephalitis virus (VEEV) utilizes all members of the Fragile X syndrome (FXR) family, while chikungunya and Sindbis viruses exploit both members of the G3BP family. Despite being in different families, these proteins share common characteristics, which determine their role in alphavirus replication, namely, the abilities for RNA-binding and for self-assembly into large structures. Both FXR and G3BP proteins interact with virus-specific, repeating amino acid sequences located in the C-termini of hypervariable, intrinsically disordered domains (HVDs) of viral nonstructural protein nsP3. We demonstrate that these host factors orchestrate assembly of vRCs and play key roles in RNA and virus replication. Only knockout of all of the homologs results in either pronounced or complete inhibition of replication of different alphaviruses. The use of multiple homologous proteins with redundant functions mediates highly efficient recruitment of viral RNA into the replication process. This independently evolved acquisition of different families of cellular proteins by the disordered protein fragment to support alphavirus replication suggests that other RNA viruses may utilize a similar mechanism of host factor recruitment for vRC assembly. The use of different host factors by alphavirus species may be one of the important determinants of their pathogenesis.
authors: Department of Microbiology, University of Alabama at Birmingham, Alabama, United States of America.
authors: Dal Young
authors: DY
authors: Kim
authors: Department of Microbiology, University of Alabama at Birmingham, Alabama, United States of America.
authors: Josephine M
authors: JM
authors: Reynaud
authors: Department of Microbiology, University of Alabama at Birmingham, Alabama, United States of America.
authors: Aliaksandra
authors: A
authors: Rasalouskaya
authors: Department of Microbiology, University of Alabama at Birmingham, Alabama, United States of America.
authors: Ivan
authors: I
authors: Akhrymuk
authors: Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.|Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.|Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.
authors: James A
authors: JA
authors: Mobley
authors: Department of Microbiology, University of Alabama at Birmingham, Alabama, United States of America.
authors: Ilya
authors: I
authors: Frolov
authors: Department of Microbiology, University of Alabama at Birmingham, Alabama, United States of America.
authors: Elena I
authors: EI
authors: Frolova
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002646:Chikungunya virus / Q000502:physiology*; D004265:DNA Helicases; D004666:Encephalitis Virus, Venezuelan Equine / Q000502:physiology*; D055786:Gene Knockout Techniques; D006790:Host-Parasite Interactions / Q000502:physiology*; D017403:In Situ Hybridization; D051379:Mice; D018613:Microscopy, Confocal; D041681:NIH 3T3 Cells; D000075223:Poly-ADP-Ribose Binding Proteins; D016133:Polymerase Chain Reaction; D020365:RNA Helicases; D000067776:RNA Recognition Motif Proteins; D012845:Sindbis Virus / Q000502:physiology*; D017361:Viral Nonstructural Proteins / Q000378:metabolism; D014779:Virus Replication / Q000502:physiology*
chemical_list: D002352:Carrier Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D000067776:RNA Recognition Motif Proteins; D017361:Viral Nonstructural Proteins; C089383:nsp3 protein, alphavirus; D004265:DNA Helicases; C492055:G3bp1 protein, mouse; D020365:RNA Helicases