Processing of M1 RNA at the 3′ End Protects Its Primary Transcript from Degradation

Alternative splicing of mRNA precursors allows the synthesis of multiple mRNAs from a single primary transcript, significantly expanding the information content and regulatory possibilities of higher eukaryotic genomes. High-throughput enabling technologies, particularly large-scale sequencing and splicing-sensitive microarrays, are providing unprecedented opportunities to address key questions in this field. The picture emerging from these pioneering studies is that alternative splicing affects most human genes and a significant fraction of the genes in other multicellular organisms, with the potential to greatly influence the evolution of complex genomes. A combinatorial code of regulatory signals and factors can deploy physiologically coherent programs of alternative splicing that are distinct from those regulated at other steps of gene expression. Pre-mRNA splicing and its regulation play important roles in human pathologies, and genome-wide analyses in this area are paving the way for improved diagnostic tools and for the identification of novel and more specific pharmaceutical targets.

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Sequence identification of cytochrome b in Plasmodium gallinaceum.

Molecular and Cellular Biology ◽

10.1128/mcb.9.9.3614 ◽

1989 ◽

Vol 9 (9) ◽

pp. 3614-3620 ◽

Cited By ~ 47

Author(s):

S M Aldritt ◽

J T Joseph ◽

D F Wirth

Keyword(s):

Cytochrome B ◽

Open Reading Frame ◽

Malarial Parasite ◽

Plasmodium Gallinaceum ◽

Primary Transcript ◽

Present Evidence ◽

Reading Frame ◽

Sequence Identification ◽

Parasite Plasmodium ◽

Extrachromosomal Element

We have identified a gene that encodes the polypeptide cytochrome b in the avian malarial parasite Plasmodium gallinaceum. The gene containing the open reading frame was found to be located on a 6.2-kilobase multimeric extrachromosomal element. The amino acid translation from this gene demonstrated significant similarities to cytochrome b sequences from yeast, mammal, and fungus genomes. We present evidence that the P. gallinaceum cytochrome b transcript is part of a larger primary transcript from the element that is subsequently processed. The message for P. gallinaceum cytochrome b was found to be 1.2 kilobases in size. This is the first report identifying a mitochondrial nucleic acid sequence in malaria-causing organisms and suggests that a functional cytochrome system may exist in these parasites.

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Three different M1 RNA-containing viruslike particle types in Saccharomyces cerevisiae: in vitro M1 double-stranded RNA synthesis

Molecular and Cellular Biology ◽

10.1128/mcb.6.5.1552-1561.1986 ◽

1986 ◽

Vol 6 (5) ◽

pp. 1552-1561

Author(s):

R Esteban ◽

R B Wickner

Keyword(s):

Saccharomyces Cerevisiae ◽

Rna Synthesis ◽

Major Coat Protein ◽

Double Stranded Rna ◽

Dsrna Molecule ◽

Protein Toxin ◽

New Type ◽

Viruslike Particles ◽

M1 Rna

Killer strains of Saccharomyces cerevisiae bear at least two different double-stranded RNAs (dsRNAs) encapsidated in 39-nm viruslike particles (VLPs) of which the major coat protein is coded by the larger RNA (L-A dsRNA). The smaller dsRNA (M1 or M2) encodes an extracellular protein toxin (K1 or K2 toxin). Based on their densities on CsCl gradients, L-A- and M1-containing particles can be separated. Using this method, we detected a new type of M1 dsRNA-containing VLP (M1-H VLP, for heavy) that has a higher density than those previously reported (M1-L VLP, for light). M1-H and M1-L VLPs are present together in the same strains and in all those we tested. M1-H, M1-L, and L-A VLPs all have the same types of proteins in the same approximate proportions, but whereas L-A VLPs and M1-L VLPs have one dsRNA molecule per particle, M1-H VLPs contain two M1 dsRNA molecules per particle. Their RNA polymerase produces mainly plus single strands that are all extruded in the case of M1-H particles but are partially retained inside the M1-L particles to be used later for dsRNA synthesis. We show that M1-H VLPs are formed in vitro from the M1-L VLPs. We also show that the peak of M1 dsRNA synthesis is in fractions lighter than M1-L VLPs, presumably those carrying only a single plus M1 strand. We suggest that VLPs carrying two M1 dsRNAs (each 1.8 kilobases) can exist because the particle is designed to carry one L-A dsRNA (4.5 kilobases).

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The additional guanylate at the 5' terminus of Escherichia coli tRNAHis is the result of unusual processing by RNase P

Molecular and Cellular Biology ◽

10.1128/mcb.6.2.525-529.1986 ◽

1986 ◽

Vol 6 (2) ◽

pp. 525-529

Author(s):

O Orellana ◽

L Cooley ◽

D Söll

Keyword(s):

Escherichia Coli ◽

Rnase P ◽

E Coli ◽

Unusual Cleavage ◽

M1 Rna

In eucaryotes the 5'-terminal guanylate moiety of mature tRNAHis is added posttranscriptionally. To determine whether the same mechanism occurs in procaryotes, we processed in vitro-derived Escherichia coli tRNAHis precursors to mature tRNA, either in E. coli extracts or by using pure M1-RNA, the catalytic component of RNase P. The results show that the extra guanylate at the 5' end of mature E. coli tRNAHis is encoded in the gene and is found in tRNA as the result of an unusual cleavage by RNase P.

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Interactions of U2 Gene Loci and Their Nuclear Transcripts with Cajal (Coiled) Bodies: Evidence for PreU2 within Cajal Bodies

Molecular Biology of the Cell ◽

10.1091/mbc.11.9.2987 ◽

2000 ◽

Vol 11 (9) ◽

pp. 2987-2998 ◽

Cited By ~ 40

Author(s):

Kelly P. Smith ◽

Jeanne Bentley Lawrence

Keyword(s):

Potential Role ◽

Coiled Body ◽

Oligonucleotide Probes ◽

Primary Transcript ◽

U2 Snrna ◽

Rna Foci ◽

Coiled Bodies ◽

Snrna Gene

The Cajal (coiled) body (CB) is a structure enriched in proteins involved in mRNA, rRNA, and snRNA metabolism. CBs have been shown to interact with specific histone and snRNA gene loci. To examine the potential role of CBs in U2 snRNA metabolism, we used a variety of genomic and oligonucleotide probes to visualize in situ newly synthesized U2 snRNA relative to U2 loci and CBs. Results demonstrate that long spacer sequences between U2 coding repeats are transcribed, supporting other recent evidence that U2 transcription proceeds past the 3′ box. The presence of bright foci of this U2 locus RNA differed between alleles within the same nucleus; however, this did not correlate with the loci's association with a CB. Experiments with specific oligonucleotide probes revealed signal for preU2 RNA within CBs. PreU2 was also detected in the locus-associated RNA foci, whereas sequences 3′ of preU2 were found only in these foci, not in CBs. This suggests that a longer primary transcript is processed before entry into CBs. Although this work shows that direct contact of a U2 locus with a CB is not simply correlated with RNA at that locus, it provides the first evidence of new preU2 transcripts within CBs. We also show that, in contrast to CBs, SMN gems do not associate with U2 gene loci and do not contain preU2. Because other evidence indicates that preU2 is processed in the cytoplasm before assembly into snRNPs, results point to an involvement of CBs in modification or transport of preU2 RNA.

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