Molecular mechanism of trans-translation.
tmRNA has a dual function as a tRNA and an mRNA to relieve the stalled ribosome. During this process, tmRNA enters the ribosomal A-site without a codonanticodon interaction, but with a protein factor SmpB. Here, we established in vitro trans-translation system, which is able to evaluate peptidyl transfer to alanyltmRNA and translation of the resume codon on tmRNA. Using this system, the effects of mutations on tmRNA or SmpB are assessed by measuring the incorporations of labeled amino acid into polypeptide. Interaction of SmpB with ribosome and tmRNA was studied by directed hydroxyl radical probing. Our results revealed that SmpB constitutes an important element during trans-translation. We propose a new model of transtranslation.
Kurita
Daisuke
D
Department of Biochemistry and Biotechnology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan.
Konno
Takayuki
T
Takada
Kazuma
K
Muto
Akira
A
Himeno
Hyouta
H
D001665:Binding Sites; D008957:Models, Genetic; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism
D012329:RNA, Bacterial; D016601:RNA-Binding Proteins; C430328:small protein B; C096222:tmRNA