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Details for article 3 of 32 found articles
| Title: |
An extended {\it Escherichia coli} ``Selenocysteine Insertion Sequence'' (SECIS) as a multifunctional RNA structure |
| Author: |
Hanna Engelberg-Kulka Zesheng Liu Chuang Li Myriam Reches |
| Appeared in: |
BioFactors |
| Paging: | Volume 14 (2001) nr. 1-4 pages 61-68 |
| Year: |
2001-08-17 |
| Contents: |
The genetic code, once thought to be rigid, has been found to permit several alternatives in its reading. Interesting alternative relates to the function of the UGA codon. Usually, it acts as a stop codon, but it can also direct the incorporation of the amino acid selenocysteine into a polypeptide. UGA-directed selenocysteine incorporation requires a cis-acting mRNA element called the ``selenocysteine insertion sequence'' (SECIS) that can form a stem-loop RNA structure. Here we discuss our investigation on the {\it E. coli} SECIS. This includes the follows: 1) The nature of the minimal {\it E. coli} SECIS. We found that in {\it E. coli} only the upper-stem and loop of 17 nucleotides of the SECIS is necessary for selenocysteine incorporation on the condition that it is located in the proper distance from the UGA [34]; 2) The upper stem and loop structure carries a bulged U residue that is required for selenocysteine incorporation [34] because of its interaction with SelB; and 3) We described an extended {\it fdhF} SECIS that includes the information for an additional function: The prevention of UGA readthrough under conditions of selenium deficiency [35]. This information is contained in a short mRNA region consisting of a single C residue adjacent to the UGA on its downstream side, and an additional segment consisting of the six nucleotides immediately upstream from it. These two regions act independently and additively and probably through different mechanisms. The single C residue acts as itself; the upstream region acts at the level of the two amino acids, arginine and valine, for which it codes. These two codons at the 5' side of the UGA correspond to the ribosomal E and P sites. Finally, we present a model for the {\it E. coli fdhF} SECIS as a multifunctional RNA structure containing three functional elements. Depending on the availability of selenium the SECIS enables one of two alternatives for the translational machinery: Either selenocysteine incorporation into a polypeptide or termination of the polypeptide chain. |
| Publisher: |
IOS Press |
| Source file: |
Elektronische Wetenschappelijke Tijdschriften |
Details for article 3 of 32 found articles
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