| Autor: |
Fargo, D. C., Hu, E., Boynton, J. E., Gillham, N. W. |
| Zdroj: |
Molecular Genetics and Genomics; October 2000, Vol. 264 Issue: 3 p291-299, 9p |
| Abstrakt: |
In this paper, we examine the effects of mutations in the 5'UTR of the chloroplastrps7transcript ofChlamydomonas reinhardtiithat reduce the stability of the mRNA. Five point mutants in therps75'UTR were selected on the basis of their failure to accumulate reporter mRNA inEscherichia coli. Each of these mutations produces alterations in the predicted higher-order structures of therps75'UTR that destabilize the mRNA.Cis-acting suppressors of these mutations have been selected inE. coliand in theC. reinhardtiichloroplast that restore message stability and function. No differences in RNA melting and reannealing profiles have been observed between wild type, original mutant, and suppressor 5'UTRs transcribed in vitro. Proteins of 32 kDa and 47 kDa that bind to the wild-typerps75'UTR are not detected by UV cross-linking assays performed with any of the mutantrps75'UTRs. However, binding of the 32-kDa protein is restored in the six suppressor mutants examined. This suggests that the 32-kDa protein may be involved in protecting therps75'UTR and the attached coding region from digestion by ribonucleases. Alternatively, the binding site for the 32-kDa protein may be independently lost in the rearranged tertiary structure of the mutant 5'UTR that exposes the RNA to degradation and is restored in the suppressor mutants. |
| Databáze: |
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