title: A multifunctional RNA recognition motif in poly(A)-specific ribonuclease with cap and poly(A) binding properties.
abstract: Poly(A)-specific ribonuclease (PARN) is an oligomeric, processive and cap-interacting 3' exoribonuclease that efficiently degrades mRNA poly(A) tails. Here we show that the RNA recognition motif (RRM) of PARN harbors both poly(A) and cap binding properties, suggesting that the RRM plays an important role for the two critical and unique properties that are tightly associated with PARN activity, i.e. recognition and dependence on both the cap structure and poly(A) tail during poly(A) hydrolysis. We show that PARN and its RRM have micromolar affinity to the cap structure by using fluorescence spectroscopy and nanomolar affinity for poly(A) by using filter binding assay. We have identified one tryptophan residue within the RRM that is essential for cap binding but not required for poly(A) binding, suggesting that the cap- and poly(A)-binding sites associated with the RRM are both structurally and functionally separate from each other. RRM is one of the most commonly occurring RNA-binding domains identified so far, suggesting that other RRMs may have both cap and RNA binding properties just as the RRM of PARN.
authors.affiliation: Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Nilsson
authors.forename: Niklas
authors.initials: N
authors.lastname: Henriksson
authors.forename: Anna
authors.initials: A
authors.lastname: Niedzwiecka
authors.forename: Nikolaos A A
authors.initials: NA
authors.lastname: Balatsos
authors.forename: Kyriakos
authors.initials: K
authors.lastname: Kokkoris
authors.forename: Jens
authors.initials: J
authors.lastname: Eriksson
authors.forename: Anders
authors.initials: A
authors.lastname: Virtanen
mesh_terms: D000225:Adenine / Q000378:metabolism; D020816:Amino Acid Motifs; D000818:Animals; D001665:Binding Sites; D017124:Conserved Sequence; D005095:Exoribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011061:Poly A / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment