title: Oligomerization activity of a double-stranded RNA-binding domain.
abstract: Xenopus laevis RNA-binding protein A (Xlrbpa) is a highly conserved, ubiquitously expressed hnRNP- and ribosome-associated RNA-binding protein that contains three double stranded RNA-binding domains (dsRBDs) in tandem arrangement. A two-hybrid screen with Xlrbpa as a bait recovered Xlrbpa itself as the strongest interaction partner, indicating multimerization of this protein. To search for regions responsible for the observed interaction, we conducted two-hybrid assays with Xlrbpa deletion constructs and identified the third dsRBD of Xlrbpa as the exclusive interacting domain. Additionally, these results were confirmed by coimmunoprecipitation experiments with truncated proteins expressed both in yeast and Xenopus oocytes. In PACT, the human homologue of Xlrbpa, we could demonstrate that the third dsRBD displays the same multimerization activity. Interestingly, this domain is essential for the activation of the dsRNA-activated protein kinase PKR. Addition of RNAses to coimmunoprecipitation experiments did not affect the dimerization, suggesting that the interaction is independent of RNA-binding. We report here a homomultimerization activity of a type B dsRBD and suggest possible implications that include a model for PKR activation by PACT.
authors.affiliation: Max F. Perutz Laboratories, Department of Cell Biology and Genetics, Institute of Botany, University of Vienna, Rennweg 14, 1030 Vienna, Austria.
authors.forename: Edward G
authors.initials: EG
authors.lastname: Hitti
authors.forename: Nina B
authors.initials: NB
authors.lastname: Sallacz
authors.forename: Vera K
authors.initials: VK
authors.lastname: Schoft
authors.forename: Michael F
authors.initials: MF
authors.lastname: Jantsch
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001704:Biopolymers; D003001:Cloning, Molecular; D017931:DNA Primers; D008969:Molecular Sequence Data; D012330:RNA, Double-Stranded / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D029867:Xenopus Proteins / Q000737:chemistry / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D001704:Biopolymers; D017931:DNA Primers; D012330:RNA, Double-Stranded; D029867:Xenopus Proteins