Neuronal BC1 RNA structure: Evolutionary conversion of a tRNAAla domain into an extended stem-loop structure
By chemical and enzymatic probing, we have analyzed the secondary structure of rodent BC1 RNA, a small brain-specific non-messenger RNA. BC1 RNA is specifically transported into dendrites of neuronal cells, where it is proposed to play a role in regulation of translation near synapses. In this study we demonstrate that the 5′ domain of BC1 RNA, derived from tRNAAla, does not fold into the predicted canonical tRNA cloverleaf structure. We present evidence that by changing bases within the tRNAAla domain during the course of evolution, an extended stem-loop structure has been created in BC1 RNA. The new structural domain might function, in part, as a putative binding site for protein(s) involved in dendritic transport of BC1 RNA within neurons. Furthermore, BC1 RNA contains, in addition to the extended stem-loop structure, an internal poly(A)-rich region that is supposedly single stranded, followed by a second smaller stem-loop structure at the 3′ end of the RNA. The three distinct structural domains reflect evolutionary legacies of BC1 RNA.(Received December 11 2000)
(Revised January 16 2001)
(Accepted January 31 2001)
Key Words: BC1 RNA; chemical probing; ID elements; neuronal dendritic RNA; secondary structure; tRNA ancestor.
c1 Reprint requests to: Jürgen Brosius, Institute of Experimental Pathology/Molecular Neurobiology, Von-Esmarch-Str. 56, 48149 Münster, Germany; e-mail: RNA.firstname.lastname@example.org.