Open AccessThe group I‐like ribozyme DiGIR1 mediates alternative processing of pre‐rRNA transcripts in Didymium iridis
Author(s) -
Vader Anna,
Johansen Steinar,
Nielsen Henrik
Publication year - 2002
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1033.2002.03283.x
Subject(s) - ribozyme , intron , biology , rna splicing , rna , mammalian cpeb3 ribozyme , group i catalytic intron , ribosomal rna , homing endonuclease , ligase ribozyme , genetics , hairpin ribozyme , microbiology and biotechnology , vs ribozyme , gene
During starvation induced encystment, cells of the myxomycete Didymium iridis accumulate a 7.5‐kb RNA that is the result of alternative processing of pre‐rRNA. The 5′ end corresponds to an internal processing site cleaved by the group I‐like ribozyme DiGIR1, located within the twin‐ribozyme intron Dir.S956‐1. The RNA retains the majority of Dir.S956‐1 including the homing endonuclease gene and a small spliceosomal intron, the internal transcribed spacers ITS1 and ITS2, and the large subunit rRNA lacking its two group I introns. The formation of this RNA implies cleavage by DiGIR1 in a new RNA context, and presents a new example of the cost to the host of intron load. This is because the formation of the 7.5‐kb RNA is incompatible with the formation of functional ribosomal RNA from the same transcript. In the formation of the 7.5‐kb RNA, DiGIR1 catalysed cleavage takes place without prior splicing performed by DiGIR2. This contrasts with the processing order leading to mature rRNA and I‐ Dir I mRNA in growing cells, suggesting an interplay between the two ribozymes of a twin‐ribozyme intron.