Cleavage site mapping and substrate-specificity of Leishmaniavirus 2-1 capsid endoribonuclease activity

The Leishmaniavirus capsid protein possesses an RNA endoribonuclease activity that cleaves viral positive-sense RNA at a specific, single site within the 5' untranslated region. The site of cleavage in LRV1-4 RNA was previously mapped to nucleotide 320 of the LRV1-4 genome. Here we show that an LRV2-1-derived substrate RNA transcript is also cleaved at a single site in an in vitro cleavage assay with LRV2-1 virions. Precise RNA cleavage site mapping in this divergent Old World virus, LRV2-1, confirms that cleavage is occurring within a region of homology to the LRV1 isolates. Substrate RNA transcripts possessing viral sequences from LRV1-4 or LRV2-1 genomes were assayed for susceptibility to cleavage by the cognate and noncognate capsid endoribonucleases to determine the level of substrate specificity.