Processing of a composite large subunit rRNA. Studies with chlamydomonas mutants deficient in maturation of the 23s-like rrna.
AUTOR(ES)
Holloway, S P
RESUMO
(Cr.LSU). Little is known of the cis and trans requirements or of the processing pathway for this essential RNA. Previous work showed that the ribosome-deficient ac20 mutant overaccumulates an unspliced large subunit (LSU) RNA, suggesting that it might be a splicing mutant. To elucidate the molecular basis of the ac20 phenotype, a detailed analysis of the rrn transcripts in ac20 and wild-type cells was performed. The results indicate that processing of the ITSs, particularly ITS-1, is inefficient in ac20 and that ITS processing occurs after splicing. Deletion of the Cr.LSU intron from ac20 also did not alleviate the mutant phenotype. Thus, the primary defect in ac20 is not splicing but most likely is associated with ITS processing. A splicing deficiency was studied by transforming wild-type cells with rrnL genes containing point mutations in the intron core. Heteroplasmic transformants were obtained in most cases, except for P4 helix mutants; these strains grew slowly, were light sensitive, and had an RNA profile indicative of inefficient splicing. Transcript analysis in the P4 mutants also indicated that ITS processing can occur on an unspliced precursor, although with reduced efficiency. These latter results indicate that although there is not an absolutely required order for LSU processing, there does seem to be a preferred order that results in efficient processing in vivo.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=144049Documentos Relacionados
- Role for the highly conserved region of domain IV of 23S-like rRNA in subunit-subunit interactions at the peptidyl transferase centre.
- A compilation of large subunit (23S- and 23S-like) ribosomal RNA structures
- Direct crosslinking of the antitumor antibiotic sparsomycin, and its derivatives, to A2602 in the peptidyl transferase center of 23S-like rRNA within ribosome-tRNA complexes
- A compilation of large subunit (23S and 23S-like) ribosomal RNA structures: 1993.
- Sequences implicated in the processing of Thermus thermophilus HB8 23S rRNA.