Restoration of a translational stop-start overlap reinstates translational coupling in a mutant trpb′-trpa gene pair of the Escherichia coli tryptophan operon

Anath Das, Charles Yanofsky

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

The trpB and trpA coding regions of the polycistronic trp mRNA of Escherichia coli are separated by overlapping translation stop and start codons. Efficient translation of the trpA coding region is subject to translational coupling, i.e., maximal trpA expression is dependent on prior translation of the trpB coding region (1,2). Previous studies demonstrated that the trpA Shine-Dalgarno sequence (within trpB) and/or the location of the trpB stop codon influenced trpA expression (2). To examine the effect of stop codon location specifically, we constructed plasmids in which different nucleotide sequences preceding the trpA start codon were retained, and only the reading frame was changed. When trpB translation proceeded in the wild type reading frame and terminated at the normal trpB stop codon, trpA polypeptide levels were elevated over the levels observed when translation stopped before or after the natural trpB stop codon. The proximity of the trpB stop codon to the trpA start codon therefore markedly influences trpA expression.

Original languageEnglish (US)
Pages (from-to)9333-9340
Number of pages8
JournalNucleic acids research
Volume17
Issue number22
DOIs
StatePublished - Nov 25 1989

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