Non-coding snoRNA host genes in Drosophila: expression strategies for modification guide snoRNAs

Authors: Tycowski K.T.; Steitz J.A.

Source: European Journal of Cell Biology, Volume 80, Number 2, February 2001 , pp. 119-125(7)

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Abstract:

Modification guide snoRNAs either are encoded within introns and co-transcribed with the host gene pre-mRNA or are independently transcribed as mono- or polycistronic units. Different eukaryotic kingdoms utilize these coding strategies to various degrees. Intron-encoded and polycistronic snoRNAs are released from primary transcripts as pre-snoRNAs by the spliceosome or by an RNase III-like activity, respectively. In the spliceosomal pathway, the resulting intron lariat is then linearized by a debranching activity. The leader and trailer sequences of pre-snoRNAs are removed by exonucleolytic activities. The majority of snoRNA host genes encode proteins involved in the synthesis, structure or function of the translational apparatus. Several vertebrate snoRNA host genes do not appear to code for functional proteins. We have identified two unusually compact box C/D multi-snoRNA host genes in D. melanogaster, dUHG1 and dUHG2, similar in their organization to the corresponding vertebrate non-protein-coding host genes. In dUHG1 and dUHG2, the snoRNA sequences are located within introns at a conserved distance of about 75 nucleotides upstream of the 3 prime splice sites. Both genes initiate transcription with TOP-like sequences that share unique features with previously reported Drosophila snoRNA host genes. Although the spliced dUHG RNAs are relatively stable, they exhibit little potential for protein coding.

Keywords: snoRNA host gene; TOP sequence; RNA modification; guide RNA

Language: English

Document Type: Original article

DOI: http://dx.doi.org/10.1078/0171-9335-00150

Affiliations: 1: Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT/USA

Publication date: 2001-02-01