In vivo expression of the nucleolar group I intron-encoded I-dirI homing endonuclease involves the removal of a spliceosomal intron

TY - JOUR

T1 - In vivo expression of the nucleolar group I intron-encoded I-dirI homing endonuclease involves the removal of a spliceosomal intron

AU - Vader, A

AU - Nielsen, Henrik

AU - Johansen, S

N1 - Keywords: Amoeba; Animals; Base Sequence; Cloning, Molecular; DNA, Ribosomal; Gene Expression Regulation; Introns; Molecular Sequence Data; Open Reading Frames; Polyribosomes; RNA Polymerase II; RNA Precursors; RNA Processing, Post-Transcriptional; RNA Splicing; RNA, Catalytic; RNA, Messenger; Sequence Analysis, DNA; Sequence Analysis, RNA; Spliceosomes

PY - 1999

Y1 - 1999

N2 - The Didymium iridis DiSSU1 intron is located in the nuclear SSU rDNA and has an unusual twin-ribozyme organization. One of the ribozymes (DiGIR2) catalyses intron excision and exon ligation. The other ribozyme (DiGIR1), which along with the endonuclease-encoding I-DirI open reading frame (ORF) is inserted in DiGIR2, carries out hydrolysis at internal processing sites (IPS1 and IPS2) located at its 3' end. Examination of the in vivo expression of DiSSU1 shows that after excision, DiSSU1 is matured further into the I-DirI mRNA by internal DiGIR1-catalysed cleavage upstream of the ORF 5' end, as well as truncation and polyadenylation downstream of the ORF 3' end. A spliceosomal intron, the first to be reported within a group I intron and the rDNA, is removed before the I-DirI mRNA associates with the polysomes. Taken together, our results imply that DiSSU1 uses a unique combination of intron-supplied ribozyme activity and adaptation to the general RNA polymerase II pathway of mRNA expression to allow a protein to be produced from the RNA polymerase I-transcribed rDNA.

AB - The Didymium iridis DiSSU1 intron is located in the nuclear SSU rDNA and has an unusual twin-ribozyme organization. One of the ribozymes (DiGIR2) catalyses intron excision and exon ligation. The other ribozyme (DiGIR1), which along with the endonuclease-encoding I-DirI open reading frame (ORF) is inserted in DiGIR2, carries out hydrolysis at internal processing sites (IPS1 and IPS2) located at its 3' end. Examination of the in vivo expression of DiSSU1 shows that after excision, DiSSU1 is matured further into the I-DirI mRNA by internal DiGIR1-catalysed cleavage upstream of the ORF 5' end, as well as truncation and polyadenylation downstream of the ORF 3' end. A spliceosomal intron, the first to be reported within a group I intron and the rDNA, is removed before the I-DirI mRNA associates with the polysomes. Taken together, our results imply that DiSSU1 uses a unique combination of intron-supplied ribozyme activity and adaptation to the general RNA polymerase II pathway of mRNA expression to allow a protein to be produced from the RNA polymerase I-transcribed rDNA.

U2 - 10.1093/emboj/18.4.1003

DO - 10.1093/emboj/18.4.1003

M3 - Journal article

C2 - 10022842

SN - 0261-4189

VL - 18

SP - 1003

EP - 1013

JO - E M B O Journal

JF - E M B O Journal

IS - 4

ER -