Open AccessSeparate structural elements within internal transcribed spacer 1 ofSaccharomyces cerevisiaeprecursor ribosomal RNA direct the formation of 17S and 26S rRNA
Author(s) -
Rob W. van Nues,
Jeanet M.J. Rientjes,
C. A. F. M. Van Der Sande,
S.F. Zerp,
C. Sluiter,
Jaap Venema,
Rudi J. Planta,
Hendrik A. Raué
Publication year - 1994
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/22.6.912
Subject(s) - biology , internal transcribed spacer , ribosomal rna , saccharomyces cerevisiae , kluyveromyces lactis , conserved sequence , genetics , kluyveromyces , phylogenetic tree , yeast , gene , peptide sequence
Structural features of Internal Transcribed Spacer 1 (ITS1) that direct its removal from Saccharomyces cerevisiae pre-rRNA during processing were identified by an initial phylogenetic approach followed by in vivo mutational analysis of specific structural elements. We found that S. cerevisiae ITS1 can functionally be replaced by the corresponding regions from the yeasts Torulaspora delbrueckii, Kluyveromyces lactis and Hansenula wingei, indicating that structural elements required in cis for processing are evolutionarily conserved. Despite large differences in size, all ITS1 regions conform to the secondary structure proposed by Yeh et al. [Biochemistry 29 (1990) 5911-5918], showing five domains (I-V; 5'-->3') of which three harbour an evolutionarily highly conserved element. Removal of most of domain II, including its highly conserved element, did not affect processing. In contrast, highly conserved nucleotides directly downstream of processing site A2 in domain III play a major role in production of 17S, but not 26S rRNA. Domain IV and V are dispensable for 17S rRNA formation although an alternative, albeit inefficient, processing route to mature 17S rRNA may be mediated by a conserved region in domain IV. Each of these two domains is individually sufficient for efficient production of 26S rRNA, suggesting two independent processing pathways. We conclude that ITS1 is organized into two functionally and structurally distinct halves.