Sequence and proposed secondary structure of the Tetrahymena thermophila U3-snRNA.
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Animals↗
Biomedical subjects
H Orum
Publications and source records attributed to H Orum.
Structural organization of the genes encoding the small nuclear RNAs U1 to U6 of Tetrahymena thermophila is very similar to that of plant small nuclear RNA genes.
We report the sequences of the genes encoding the small nuclear RNAs (snRNAs) U1 to U6 of the ciliate Tetrahymena thermophila. The genes of the individual snRNAs exist in two to six slightly different copies per haploid genome. Sequence analyses of the gene-flanking regions indicate that there are two classes of snRNA genes. Both classes are characterized by several conserved sequence elements, some of which are unique to each class and some of which are found in both classes. Comparison of the promoter structure of the snRNA genes of T. thermophila with the promoter structures of snRNA genes of other organisms revealed several similarities to plant snRNA genes. These similarities include the overall promoter architecture as well as specific sequence elements. The structural organization of the 3' flanking region of some of the T. thermophila snRNA genes is not observed in other organisms. This finding is discussed in relation to a possible role in snRNA 3'-end formation.
Animals↗
A novel class of nucleolar RNAs from Tetrahymena.
We describe a family of at least four nucleolar RNAs (snoRNAs) from the ciliate, Tetrahymena. The snoRNAs are 120-140 nucleotides long, moderately AU-rich and contain no modified nucleotides. Their 5' ends are blocked by a cap of unknown nature. The snoRNAs can be folded into similar secondary structures consisting of two hairpins separated by a single-stranded AU-rich spacer. The sequences and secondary structures show no extensive sequence or secondary structure resemblance to any other small RNAs in the public databases.
Animals↗
Sequence of a new snRNA from the ciliate Tetrahymena thermophila.
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Animals↗
Expression in E. coli of the gene encoding phenylalanine ammonia-lyase from Rhodosporidium toruloides.
The active sites of the enzyme phenylalanine ammonia-lyase (Pal) from Rhodosporidium toruloides contains a dehydroalanine residue that is believed to be essential for catalytic activity. Furthermore, the dehydroalanine is believed to be added post-translationally as part of a prosthetic group covalently attached to the enzyme. Perhaps for this reason no attempts to produce Pal in foreign host cells have been reported. We have inserted the entire uninterupted pal gene from R. toruloides into the Escherichia coli expression vector pKK 223-3. E. coli cells containing this vector synthesize a protein of the expected size, and extracts prepared from these cells contain a Pal-like activity. The potential implications of this finding are discussed.
Base Sequence↗
Spliceosomal small nuclear RNAs of Tetrahymena thermophila and some possible snRNA-snRNA base-pairing interactions.
We have identified and characterized the full set of spliceosomal small nuclear RNAs (snRNAs; U1, U2, U4, U5 and U6) from the ciliated protozoan Tetrahymena thermophila. With the exception of U4 snRNA, the sizes of the T. thermophila snRNAs are closely similar to their metazoan homologues. The T. thermophila snRNAs all have unique 5' ends, which start with an adenine residue. In contrast, with the exception of U6, their 3' ends show some size heterogeneity. The primary sequences of the T. thermophila snRNAs contain the sequence motifs shown, or proposed, to be of functional importance in other organisms. Furthermore, secondary structures closely similar to phylogenetically proven models can be inferred from the T. thermophila data. Analysis of the snRNA sequences identifies three potential snRNA-snRNA base-pairing interactions, all of which are consistent with available phylogenetic data. Two of these occur between U2 and U6, whereas the third occurs between U1 and U2. The proposed interactions locate the intron 5' splice-site close to the intron branch-site nucleotide as well as to the most highly conserved domain of U6. We envisage that these interactions may facilitate the first step of pre-mRNA splicing.
Animals↗
A novel, single plasmid, approach to in-frame fusion.
The sequence GCGCGCGCGC contains three overlapping, mutually exclusive, BssHII restriction sites, each corresponding to one of the three different reading frames. When inserted into a plasmid and digested with BssHII, the three sites in this sequence are cleaved at an approximate ratio of 2:1:2. Consequently, this system can be used to simplify in vitro in frame fusions to involve a single plasmid. We have constructed such a plasmid and used it to select an open reading frame in a 1.6 kb cDNA fragment.
DNA↗