Isolation and sequence of four small nuclear U RNA genes of Trypanosoma brucei subsp. brucei: Identification of the U2, U4, and U6 RNA analogs
- Glasgow Univ. (UK)
- California Univ., San Francisco, CA (USA). School of Medicine
- Universidad Nacional Autonoma de Mexico, Mexico City (Mexico)
- Max-Planck-Institut fuer Molekulare Genetik, Berlin (Germany, F.R.)
- California Univ., San Francisco, CA (USA). Dept. of Pharmaceutical Chemistry
Trypanosomes use trans splicing to place a common 39-nucleotide spliced-leader sequence on the 5' ends of all of their mRNAs. To identify likely participants in this reaction, the authors used antiserum directed against the characteristic U RNA 2,2,7-trimehtylguanosine (TMG) cap to immunoprecipitate six candidate U RNAs from total trypanosome RNA. Genomic Southern analysis using oligonucleotide probes constructed frm partial RNA sequence indicated that the four largest RNAs (A through D) are encoded by single-copy genes that are not closely linked to one another. The authors have cloned and sequenced these genes, mapped the 5' ends of the encoded RNAs,and identified three of the RNAs as the trypanosome U2, U4, and U6 analogs by virtue of their sequences and structural homologies with the corresponding metazoan U RNAs. The fourth RNA, RNA B (144 nucleotides), was not sufficiently similar to known U RNAs to allow them to propose an identity. Surprisingly, none of the U RNAs contained the consensus Sm antigen-binding site, a feature totally conserved among several classes of U RNAs, including U2 and U4. Similarly, the sequence of the U2 RNA region shown to be involved in pre-mRNA branchpoint recognition in yeast, and exactly conserved in metazoan U2 RNAs, was totally divergent in trypanosomes. Like all other U6 RNAs, trypanosome U6 did not contain a TMG cap and was immunoprecipitated from deproteinized RNA by anti-TMG antibody because of its association with the TMG-capped U4 RNA. These two RNAs contained extensive regions of sequence complementarity which phylogenetically support the secondary-structure model proposed by D.A. Brow and C. Guthrie (Nature (London) 334:213-218, 1988) for the organization of the analogous yeast U4-U6 complex.
- OSTI ID:
- 5643368
- Journal Information:
- Molecular and Cellular Biology; (USA), Vol. 9:3; ISSN 0270-7306
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MESSENGER-RNA
DNA SEQUENCING
TRYPANOSOMA
GENETIC MAPPING
ANTIBODIES
DNA-CLONING
GENES
OLIGONUCLEOTIDES
RNA
ANIMALS
CLONING
DNA HYBRIDIZATION
HYBRIDIZATION
INVERTEBRATES
MAPPING
MASTIGOPHORA
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PARASITES
PROTOZOA
STRUCTURAL CHEMICAL ANALYSIS
550200* - Biochemistry