5'-end formation of yeast 5.8SL rRNA is an endonucleolytic event.
Like most eukaryotes, Saccharomyces cerevisiae cells contain a minor 5.8SL rRNA that, relative to the major 5.8SS species, carries several extra nucleotides at the 5'-end. The two species are produced by alternative pathways that differ in the events removing the 3'-terminal region of Internal Transcribed Spacer 1 from the 27SA2 pre-rRNA. Whereas the pathway leading to 5.8SS rRNA is well established, that producing the 5'-end of 5.8SL (called B1L) is poorly understood. Northern analysis of two different mutants of S. cerevisiae that overproduce 5.8SL rRNA revealed the presence of a fragment corresponding to the 3'-terminal region of Internal Transcribed Spacer 1 (ITS1) directly upstream from site B1L. Immunoprecipitation experiments showed this fragment to be associated with the trans-acting factor Rrp5p required for processing at the early sites A0-A3. Together these data clearly support that the 5'-end of 5.8SL rRNA is an endonucleolytic event. In vivo mutational analysis demonstrated the lack of any cis-acting sequence elements directing this cleavage within ITS1.
Faber
Alex W
AW
Section Biochemistry and Molecular Biology, Department of Chemistry, Faculty of Sciences and Institute Molecular Biology Science, BioCenter Amsterdam, Vrije Universiteit, Amsterdam, The Netherlands.
Vos
Harmjan R
HR
Vos
Jan C
JC
Raué
Hendrik A
HA
D001483:Base Sequence; D004252:DNA Mutational Analysis; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D047468:Immunoprecipitation; D012340:RNA, Ribosomal, 5.8S / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*
D021903:DNA, Ribosomal Spacer; D012340:RNA, Ribosomal, 5.8S; D004722:Endoribonucleases