Identification of an Alternative rRNA Post-transcriptional Maturation of 26S rRNA in the Kingdom Fungi

Despite of the integrity of their RNA, some desert truffles present a non-canonicalprofile of rRNA where 3.3 kb is absent, 1.8 kb is clear and a band of 1.6 kb isobserved. A similar rRNA profile was identified in organisms belonging to differentlife kingdoms, with the exception of the Kingdom Fungi, as a result of a split LSUrRNA called hidden gap. rRNA profiles of desert truffles were analyzed to verify thepresence of the non-canonical profile. The RNA of desert truffles and yeast were blottedand hybridized with probes complementary to LSU extremes. RACE of LSU rRNAwas carried out to determine the LSU rRNA breakage point. LSU rRNA of deserttruffles presents a post-transcriptional cleavage of five nucleotides that generates ahidden gap located in domain D7. LSU splits into two molecules of 1.6 and 1.8 kb.Similar to other organisms, a UAAU tract, downstream of the breakage point, wasidentified. Phylogenetic comparison suggests that during fungi evolution mutations wereintroduced in the hypervariable D7 domain, resulting in a sequence that is specificallypost-transcriptionally cleaved in some desert truffles.