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Expression of the Escherichia coli pcnB gene is translationally limited using an inefficient start codon: a second chromosomal example of translation initiated at AUU
Author(s) -
Binns Nigel,
Masters Millicent
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02945.x
Subject(s) - biology , start codon , gene , escherichia coli , translation (biology) , eukaryotic translation , genetics , stop codon , codon usage bias , protein biosynthesis , messenger rna , microbiology and biotechnology , genome
Summary Expression of the gene pcnB , encoding the dispensable Escherichia coli poly(A) polymerase (PAPI), which is toxic when overproduced, was investigated. Its promoter was identified and found to be moderately strong when used to express a β‐galactosidase reporter. Expression levels were not affected by increasing or decreasing PcnB concentration. Translation of pcnB was found to initiate from the non‐canonical initiation codon AUU. The only other coli gene reported to use AUU as initiation codon is infC , which encodes the initiation factor IF‐3. AUU, in common with other rarely used initiation codons, is discriminated against by IF‐3, resulting in the aborting of most AUU‐promoted initiation events. This enables AUU to form part of an autoregulatory circuit controlling IF‐3 production. We show that InfC discrimination reduces PcnB production fivefold. This is the first instance of this mechanism being used to limit severely the production of a potentially toxic product.