Synthetic lethal interactions with conditional poly(A) polymerase alleles identify LCP5, a gene involved in 18S rRNA maturation.

To identify new genes involved in 3'-end formation of mRNAs in Saccharomyces cerevisiae, we carried out a screen for synthetic lethal mutants with the conditional poly(A) polymerase allele, pap1-7. Five independent temperature-sensitive mutations called Icp1 to Icp5 (for lethal with conditional pap1 allele) were isolated. Here, we describe the characterization ...
of the essential gene LCP5 which codes for a protein with a calculated molecular mass of 40.8 kD. Unexpectedly, we found that mutations in LCP5 caused defects in pre-ribosomal RNA (pre-rRNA) processing, whereas mRNA 3'-end formation in vitro was comparable to wild-type. Early cleavage steps (denoted A0 to A2) that lead to the production of mature 18S rRNA were impaired. In vivo depletion of Lcp5p also inhibited pre-rRNA processing. As a consequence, mutant and depleted cells showed decreased levels of polysomes compared to wild-type cells. Indirect immunofluorescence indicated a predominant localization of Lcp5p in the nucleolus. In addition, antibodies directed against Lcp5p specifically immunoprecipitated the yeast U3 snoRNA snR17, suggesting that the protein is directly involved in pre-rRNA processing.
Mesh Terms:
Alleles, Amino Acid Sequence, Basic-Leucine Zipper Transcription Factors, DNA-Binding Proteins, Fungal Proteins, Genes, Essential, Genes, Fungal, Genes, Lethal, Molecular Sequence Data, Mutagenesis, Nuclear Proteins, Phenotype, Polynucleotide Adenylyltransferase, Polyribosomes, Protein Biosynthesis, RNA Processing, Post-Transcriptional, RNA, Fungal, RNA, Ribosomal, 18S, RNA, Small Nuclear, RNA-Binding Proteins, Ribosomes, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Schizosaccharomyces pombe Proteins
RNA
Date: Nov. 01, 1998
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