Autoregulation of the tufB operon in Salmonella
2016 (English)In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 100, no 6, 1004-1016 p.Article in journal (Refereed) Published
In Salmonella enterica and related species, translation elongation factor EF-Tu is encoded by two widely separated but near-identical genes, tufA and tufB. Two thirds of EF-Tu is expressed from tufA with the remaining one third coming from tufB. Inactivation of tufA is partly compensated by a doubling in the amount of EF-TuB but the mechanism of this up-regulation is unknown. By experimental evolution selecting for improved growth rate in a strain with an inactive tufA we selected six different noncoding or synonymous point mutations close to the tufB start codon. Based on these results we constructed a total of 161 different point mutations around the tufB start codon, as well as tufB 3'-truncations, and measured tufB expression using tufB-yfp transcriptional and translational fusions. The expression data support the presence of two competing stem-loop structures that can form in the 5'-end of the tufB mRNA. Formation of the 'closed' structure leads to Rho-dependent transcriptional termination of the tufB mRNA. We propose a model in which translational speed is used as a sensor for EF-Tu concentration and where the expression of tufB is post-transcriptionally regulated. This model describes for the first time how expression of the most abundant Salmonella protein is autoregulated.
Place, publisher, year, edition, pages
2016. Vol. 100, no 6, 1004-1016 p.
Salmonella enterica, tufA, tufB, EF-Tu, Rho, post-transcriptional regulation
Microbiology in the medical area
Research subject Biology with specialization in Microbiology; Microbiology; Molecular Genetics
IdentifiersURN: urn:nbn:se:uu:diva-235218DOI: 10.1111/mmi.13364ISI: 000379687100008PubMedID: 26934594OAI: oai:DiVA.org:uu-235218DiVA: diva2:759347
FunderKnut and Alice Wallenberg Foundation, KAW 2009.0251Swedish Research Council, 621-2012-2188; 521-2013-2904