Evidence for endonucleolytic cleavage at the 5′-proximal segment of the trp messenger RNA in Escherichia coli
✍ Scribed by Kano, Yasunobu ;Imamoto, Fumio
- Publisher
- Springer
- Year
- 1979
- Tongue
- English
- Weight
- 593 KB
- Volume
- 172
- Category
- Article
- ISSN
- 0026-8925
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✦ Synopsis
The 5'-proximal trp leader RNA segment (about 5S) decays at 2 to 3 times slower rates than the distal trp mRNA sequence. This has been demonstrated by employing the deletion mutants which lack a large portion of the structural genes but retain the promoter-proximal region of the trp operon. Relative stability of the leader RNA is not merely due to the presence of an untranslatable region in the segment; the internal untranslatable segment of trp mRNA downstream from the nonsense alteration site of a double mutant trpAD28.trpE9758 decays as fast as the normal trp mRNA sequence. These results suggest that the trp mRNA is endonucleolytically cleaved to yield the small 5'-proximal leader RNA segment before the distal mRNA decays and that the leader RNA sequence is not subject to usual mode of mRNA decay in the 5' to 3' direction.