A SECONDARY-STRUCTURE MODEL FOR THE SELF-CLEAVING REGION OF NEUROSPORA VS RNA

Neurospora VS RNA performs an RNA-mediated self-cleavage reaction whos e products contain 2',3'-cyclic phosphate and 5'-hydroxyl termini. Thi s reaction is similar to those of hammerhead, hairpin, and hepatitis d elta virus ribozymes; however, VS RNA is not similar in sequence to th ese other self-cleaving motifs. Here we propose a model for the second ary structure of the self-cleaving region of VS RNA, supported by site -directed mutagenesis and chemical modification structure probing data , The secondary structure of VS RNA is distinct from those of the othe r naturally occurring RNA self-cleaving domains. In addition to a uniq ue secondary structure, several Mg-dependent interactions occur during the folding of VS RNA into its active tertiary conformation.