Open AccessCrystallization of oligonucleotides containing A‐rich repeats suggests a structural contribution to the autoregulation mechanism of PABP translation
Author(s) -
Kikuchi Keita,
Shimizu Satoru,
Sato Yoshiteru,
Morishita Ella Czarina,
Takénaka Akio
Publication year - 2012
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309111052110
Subject(s) - poly(a) binding protein , messenger rna , untranslated region , oligonucleotide , biology , microbiology and biotechnology , translation (biology) , three prime untranslated region , dna , biochemistry , gene
Eukaryotic poly(A)‐binding protein (PABP) commonly binds to the 3′‐UTR poly(A) tail of every mRNA, but it also binds to the 5′‐UTR of PABP mRNA for autoregulation of its expression. In the sequence of the latter binding site, the contiguous A residues are segmented discretely by the insertion of short pyrimidine oligonucleotides as linkers, so that (A) 6–8 segments are repeated six times. This differs from the poly(A)‐tail sequence, which has a higher binding affinity for PABP. In order to examine whether the A‐rich repeats have a functional structure, several RNA/DNA analogues were subjected to crystallization. It was found that some of them could be crystallized. Single crystals thus obtained diffracted to 4.1 Å resolution. The fact that the repeated sequences can be crystallized suggests the possibility that the autoregulatory sequence in PABP mRNA has a specific structure which impedes the binding of PABP. When PABP is excessively produced, it could bind to this sequence by releasing the structure in order to interfere with initiation‐complex formation for suppression of PABP translation. Otherwise, PABP at low concentration preferentially binds to the poly(A) tail of PABP mRNA.