Open AccessLack of a 5' non-coding region in Tn1721encodedtetRmRNA is associated with a low efficiency of translation and a short half-life inEscherichia coil
Author(s) -
Ralf Baumeister,
Peter Flache,
Öjar Melefors,
Alexander von Gabain,
Wolfgang Hillen
Publication year - 1991
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/19.17.4595
Subject(s) - tetr , biology , coding region , untranslated region , lac operon , messenger rna , repressor , microbiology and biotechnology , translation (biology) , gene , genetics , gene expression
The repressor-encoding tetR gene from Tn1721 is expressed with a very low efficiency. Its mRNA lacks an untranslated leader sequence. We have constructed protein fusions with the lacZ gene which contain between 14 and 157 5' nucleotides from the tetR gene. Since they are all expressed with similar efficiencies we conclude that the sequence information for initiation of translation is contained within the first 14 bases of the tetR coding region. These fusion transcripts are about 20-fold less efficiently translated than the wild type lacZ transcript. A toeprint analysis confirms that the initiation complex is indistinguishable from those formed by regular transcripts with 5' untranslated regions but occurs in a very low amount in vitro. Thus, the absence of a 5' leader causes a poor rate of translation initiation. The half-lives of tetR and tetR-lacZ mRNAs are about 30 seconds, which is 3-times lower than that of the wt lacZ mRNA. Inactivation of the ams/rne locus in E. coli stabilizes the tetR transcript more than ten-fold. The influence of translation on the tetR half-life is discussed.