Feedback inhibition of poly(A)-binding protein mRNA translation. A possible mechanism of translation arrest by stalled 40 S ribosomal subunits.
An adenine-rich cis element at the 5'-untranslated region (UTR) of Pabp1 mRNA is able to inhibit translation of its own mRNA. Similar inhibition of translation of a reporter beta-galactosidase mRNA is observed when the adenine-rich auto regulatory sequence (ARS) is placed within the 5'-UTR of this mRNA. For this translational control the distance of the ARS from the 5' cap is not important. However, it determines the number of 40 S ribosomal subunits bound to the translationally arrested mRNA. Inhibition of mRNA translation by this regulatory sequence occurs at the step of joining of the 60 S ribosomal subunit to the pre-initiation complex. Translational arrest of the ARS containing mRNA in a rabbit reticulocyte lysate cell-free system in the presence of exogenous Pabp1 protects the 5'-flanking region of the ARS from nuclease digestion. This protection depends on the binding of the 40 S ribosomal subunit to the mRNA. The size and the sequence of the nucleotide-protected fragment depends on the location of the ARS within the 5'-UTR. When the ARS is located at a distance of about 78 nucleotides from the 5' cap, a 40-nucleotide long region adjacent to the ARS is protected. On the other hand, when the ARS is moved further away from the 5' cap to a distance of approximately 267 nucleotides, a 100-nucleotide-long region adjacent to the ARS is protected from nuclease digestion. Nuclease protection is attributed to the presence of one or more stalled 40 S ribosomal subunits near the Pabp1-bound ARS.
Bag
J
J
Department of Molecular Biology and Genetics, University of Guelph, Guelph, Ontario N1G 2W1, Canada. jbag@uoguelph.ca
D020121:5' Untranslated Regions; D000818:Animals; D002474:Cell-Free System; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008836:Micrococcal Nuclease / Q000378:metabolism; D008954:Models, Biological; D008957:Models, Genetic; D010957:Plasmids / Q000378:metabolism; D039102:Poly(A)-Binding Proteins; D011485:Protein Binding; D014176:Protein Biosynthesis; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011817:Rabbits; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection; D001616:beta-Galactosidase / Q000378:metabolism
D020121:5' Untranslated Regions; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; D012313:RNA; D015500:Chloramphenicol O-Acetyltransferase; D008836:Micrococcal Nuclease; D001616:beta-Galactosidase