Enhancement of translation by the downstream box does not involve base pairing of mRNA with the penultimate stem sequence of 16S rRNA.
The downstream box (DB) is a sequence element that enhances translation of several bacterial and phage mRNAs. It has been proposed that the DB enhances translation by base pairing transiently to bases 1469-1483 of 16S rRNA, the so-called anti-DB, during the initiation phase of translation. We have tested this model of enhancer action by constructing mutations in the anti-DB that alter its mRNA base-pairing potential and examining expression of a variety of DB-containing mRNAs in strains expressing the mutant anti-DB 16S rRNA. We found that the rRNA mutant was viable and that expression of all tested DB-containing mRNAs was completely unaffected by radical alterations in the proposed anti-DB. These findings lead us to conclude that enhancement of translation by the DB does not involve mRNA-rRNA base pairing.
O'Connor
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J. W. Wilson Laboratory, Department of Molecular and Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA. Michael_O'Connor@Brown.edu
Asai
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Squires
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Dahlberg
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D001426:Bacterial Proteins / Q000235:genetics; D020029:Base Pairing; D001483:Base Sequence; D004742:Enhancer Elements, Genetic; D004926:Escherichia coli / Q000235:genetics*; D006360:Heat-Shock Proteins / Q000235:genetics*; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D010957:Plasmids; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012808:Sigma Factor; D014157:Transcription Factors / Q000235:genetics*
D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D012333:RNA, Messenger; D012336:RNA, Ribosomal, 16S; D012808:Sigma Factor; D014157:Transcription Factors; C069774:heat-shock sigma factor 32