title: An influenza virus replicon system in yeast identified Tat-SF1 as a stimulatory host factor for viral RNA synthesis.
abstract: Influenza viruses infect vertebrates, including mammals and birds. Influenza virus reverse-genetics systems facilitate the study of the structure and function of viral factors. In contrast, less is known about host factors involved in the replication process. Here, we developed a replication and transcription system of the negative-strand RNA genome of the influenza virus in Saccharomyces cerevisiae, which depends on viral RNAs, viral RNA polymerases, and nucleoprotein (NP). Disruption of SUB2 encoding an orthologue of human RAF-2p48/UAP56, a previously identified viral RNA synthesis stimulatory host factor, resulted in reduction of the viral RNA synthesis rate. Using a genome-wide set of yeast single-gene deletion strains, we found several host factor candidates affecting viral RNA synthesis. We found that among them, Tat-SF1, a mammalian homologue of yeast CUS2, was a stimulatory host factor in influenza virus RNA synthesis. Tat-SF1 interacted with free NP, but not with NP associated with RNA, and facilitated formation of RNA-NP complexes. These results suggest that Tat-SF1 may function as a molecular chaperone for NP, as does RAF-2p48/UAP56. This system has proven useful for further studies on the mechanism of influenza virus genome replication and transcription.
authors.affiliation: Department of Infection Biology, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan.
authors.forename: Tadasuke
authors.initials: T
authors.lastname: Naito
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Kiyasu
authors.forename: Kenji
authors.initials: K
authors.lastname: Sugiyama
authors.forename: Ayumi
authors.initials: A
authors.lastname: Kimura
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Nakano
authors.forename: Akio
authors.initials: A
authors.lastname: Matsukage
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Nagata
mesh_terms: D016679:Genome, Viral; D006801:Humans; D009975:Orthomyxoviridae / Q000235:genetics* / Q000502:physiology; D012367:RNA, Viral / Q000096:biosynthesis*; D012093:Replicon; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics*; D014779:Virus Replication
chemical_list: C101819:HTATSF1 protein, human; D012367:RNA, Viral; D015534:Trans-Activators