title: A novel archaeal regulatory protein, Sta1, activates transcription from viral promoters.
abstract: While studying gene expression of the rudivirus SIRV1 in cells of its host, the hyperthermophilic crenarchaeon Sulfolobus, a novel archaeal transcriptional regulator was isolated. The 14 kDa protein, termed Sulfolobus transcription activator 1, Sta1, is encoded on the host chromosome. Its activating effect on transcription initiation from viral promoters was demonstrated in in vitro transcription experiments using a reconstituted host system containing the RNA polymerase, TATA-binding protein (TBP) and transcription factor B (TFB). Most pronounced activation was observed at low concentrations of either of the two transcription factors, TBP or TFB. Sta1 was able to bind viral promoters independently of any component of the host pre-initiation complex. Two binding sites were revealed by footprinting, one located in the core promoter region and the second approximately 30 bp upstream of it. Comparative modeling, NMR and circular dichroism of Sta1 indicated that the protein contained a winged helix-turn-helix motif, most probably involved in DNA binding. This strategy of the archaeal virus to co-opt a host cell regulator to promote transcription of its genes resembles eukaryal virus-host relationships.
authors.affiliation: Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, 25-28 rue du Dr Roux, 75724 Paris Cedex 15, France.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kessler
authors.forename: Guennadi
authors.initials: G
authors.lastname: Sezonov
authors.forename: J Iñaki
authors.initials: JI
authors.lastname: Guijarro
authors.forename: Nicole
authors.initials: N
authors.lastname: Desnoues
authors.forename: Thierry
authors.initials: T
authors.lastname: Rose
authors.forename: Muriel
authors.initials: M
authors.lastname: Delepierre
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Bell
authors.forename: David
authors.initials: D
authors.lastname: Prangishvili
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000302:isolation & purification; D015967:Gene Expression Regulation, Viral; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D023642:Rudiviridae / Q000235:genetics*; D016415:Sequence Alignment; D016944:Sulfolobus / Q000235:genetics / Q000821:virology*; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
chemical_list: D019843:Archaeal Proteins; D004268:DNA-Binding Proteins; D015534:Trans-Activators