Non-canonical mechanism for translational control in bacteria: synthesis of ribosomal protein S1.
Translation initiation region (TIR) of the rpsA mRNA encoding ribosomal protein S1 is one of the most efficient in Escherichia coli despite the absence of a canonical Shine-Dalgarno-element. Its high efficiency is under strong negative autogenous control, a puzzling phenomenon as S1 has no strict sequence specificity. To define sequence and structural elements responsible for translational efficiency and autoregulation of the rpsA mRNA, a series of rpsA'-'lacZ chromosomal fusions bearing various mutations in the rpsA TIR was created and tested for beta-galactosidase activity in the absence and presence of excess S1. These in vivo results, as well as data obtained by in vitro techniques and phylogenetic comparison, allow us to propose a model for the structural and functional organization of the rpsA TIR specific for proteobacteria related to E.coli. According to the model, the high efficiency of translation initiation is provided by a specific fold of the rpsA leader forming a non-contiguous ribosome entry site, which is destroyed upon binding of free S1 when it acts as an autogenous repressor.
Boni
I V
IV
Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117871 Moscow, Russia. irina@humgen.siobc.ras.ru
Artamonova
V S
VS
Tzareva
N V
NV
Dreyfus
M
M
D020121:5' Untranslated Regions; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D010442:Peptide Chain Initiation, Translational; D010802:Phylogeny; D014176:Protein Biosynthesis; D020560:Proteobacteria / Q000235:genetics; D012329:RNA, Bacterial / Q000737:chemistry*; D012269:Ribosomal Proteins / Q000096:biosynthesis* / Q000235:genetics
D020121:5' Untranslated Regions; D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012269:Ribosomal Proteins; C015494:ribosomal protein S1