title: The mRNA-binding site of annexin A2 resides in helices C-D of its domain IV.
abstract: Annexin A2 (AnxA2) is a Ca(2+)-binding and phospholipid-binding protein involved in different intracellular processes including exocytosis, endocytosis and membrane-cytoskeleton movements. We have previously identified AnxA2 as an mRNA-binding protein present in cytoskeleton-bound polysomes, that binds to a specific approximately 100 nucleotide region in the 3'-untranslated region of c-myc and its cognate mRNA. In the present study, we show by UV cross-linking assays and surface plasmon resonance analyses that the mRNA-binding site of AnxA2 resides in its domain IV. Furthermore, the interaction of full-length AnxA2 with the 3'-untranslated region of anxA2 mRNA is Ca(2+)-dependent. By contrast, the interaction is Ca(2+)-independent for the isolated domain IV of AnxA2, suggesting that the mRNA-binding site is masked in Apo-AnxA2 and gains exposure through a Ca(2+)-induced conformational change of AnxA2 generating a favourable mRNA-binding site. The AnxA2-mRNA interaction is specific and involves helices C and D in domain IV of AnxA2, since point mutagenesis of several charged and polar exposed residues of these helices in the full-length protein strongly reduce RNA binding. The interaction appears to be sequential involving an initial phase of recognition dominated by electrostatic interactions, most likely between lysine residues and the phosphate backbone of RNA, followed by a second phase contributing to the specificity of the interaction.
authors: Department of Biomedicine, University of Bergen, Jonas Lies Vei 91, N-5009 Bergen, Norway.
authors: Ingvild
authors: I
authors: Aukrust
authors: Hanne
authors: H
authors: Hollås
authors: Elin
authors: E
authors: Strand
authors: Lasse
authors: L
authors: Evensen
authors: Gilles
authors: G
authors: Travé
authors: Torgeir
authors: T
authors: Flatmark
authors: Anni
authors: A
authors: Vedeler
mesh_terms: D020413:3' Untranslated Regions; D000595:Amino Acid Sequence; D000818:Animals; D017306:Annexin A2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002417:Cattle; D002942:Circular Dichroism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017354:Point Mutation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism*; D016415:Sequence Alignment; D020349:Surface Plasmon Resonance; D014466:Ultraviolet Rays
chemical_list: D020413:3' Untranslated Regions; D017306:Annexin A2; D012333:RNA, Messenger