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Structure and biogenesis of small nucleolar RNAs acting as guides for ribosomal RNA modification

100%

Filipowicz W., Pelczar P., Pogacic V., Dragon F.

Acta Biochimica Polonica

1999

tom 46

nr 2

Maturation of pre-ribosomal RNA (pre-rRNA) in eukaryotic cells takes place in the nucleolus and involves a large number of cleavage events, which frequently follow alternative pathways. In addition, rRNAs are extensively modified, with the methylation of the 2'-hydroxyl group of sugar residues and conversion of uridines to pseudouridines being the most frequent modifications. Both cleavage and modification reactions of pre-rRNAs are assisted by a variety of small nucleolar RNAs (snoRNAs), which function in the form of ribonucleoprotein particles (snoRNPs). The majority of snoRNAs acts as guides directing site-specific 2'-O-ribose methylation or pseudouridine formation. Over one hundred RNAs of this type have been identified to date in vertebrates and the yeast Saccharomyces cerevisiae. This number is readily explained by the findings that one snoRNA acts as a guide usually for one or at most two modifications, and human rRNAs contain 91 pseudouridines and 106 2'-O-methyl residues. In this article we review information about the biogenesis, structure and function of guide snoRNAs.

The KRR1 gene encodes a protein required for 18S rRNA synthesis and 40S ribosomal subunit assembly in Saccharomyces cerevisiae

100%

Gromadka R., Rytka J.

Acta Biochimica Polonica

2000

tom 47

nr 4

The newly discovered Saccharomyces cerevisiae gene KRR1 (YCL059c) encodes a protein essential for cell viability. Krr1p contains a motif of clustered basic amino acids highly conserved in the evolutionarly distant species from yeast to human. We demonstrate that Krr1p is localized in the nucleolus. The KRR1 gene is highly expressed in dividing cells and its expression ceases almost completely when cells enter the stationary phase. In vivo depletion of Krr1p leads to drastic reduction of 40S ribosomal subunits due to defective 18S rRNA synthesis. We propose that Krr1p is required for proper processing of pre-rRNA and the assembly of preribosomal 40S subunits.

Ograniczanie wyników

2 Acta Biochimica Polonica

1 Dragon F.

1 Filipowicz W.

1 Gromadka R.

1 Pelczar P.

1 Pogacic V.

1 Rytka J.

1 2000

1 1999

Wyniki wyszukiwania

Structure and biogenesis of small nucleolar RNAs acting as guides for ribosomal RNA modification

The KRR1 gene encodes a protein required for 18S rRNA synthesis and 40S ribosomal subunit assembly in Saccharomyces cerevisiae