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Structure and processing of yeast precursor tRNAs containing intervening sequences
Nature
|August 3, 1978
Summary
Researchers isolated yeast precursor tRNATyr, revealing an intervening sequence and altered anticodon loop structure. This precursor is inactive until processed into mature tRNATyr by a nuclear excision-ligase activity.
Area of Science:
- Molecular Biology
- RNA Processing
- Yeast Genetics
Background:
- Transfer RNA (tRNA) molecules are crucial for protein synthesis.
- Post-transcriptional modifications, including intron splicing, are essential for tRNA maturation.
- Yeast tRNATyr gene is known to contain an intervening sequence.
Purpose of the Study:
- To characterize the structure and function of yeast pre-tRNATyr.
- To identify the enzymatic activity responsible for processing pre-tRNATyr.
- To understand the role of the intervening sequence in tRNA maturation.
Main Methods:
- Isolation and characterization of pre-tRNATyr.
- Conformational analysis using S1 nuclease sensitivity.
- Assay of nuclear extracts for processing activity.
Main Results:
- Pre-yeast tRNATyr contains an intervening sequence identical to the gene.
- The precursor's anticodon loop is conformationally distinct and sensitive to cleavage.
- Pre-tRNATyr is functionally inactive, lacking aminoacylation and proper anticodon accessibility.
- Yeast nuclear extracts possess an excision-ligase activity that matures pre-tRNATyr.
Conclusions:
- Yeast pre-tRNATyr processing involves the removal of an intervening sequence.
- A specific nuclear excision-ligase activity is responsible for generating mature tRNATyr.
- The conformational changes in the anticodon loop are critical for precursor recognition and processing.