A team of Swiss microbiologists has retracted their 2012 paper in PLoS One on the genetics of the TB mycobacterium after learning that the fusion protein they thought they’d used in their study was in fact a different molecule.
Here’s the retraction notice for the article, “A β-lactamase based reporter system for ESX dependent protein translocation in mycobacteria,” which has been cited once, according to Thomson Scientific’s Web of Knowledge:
The authors request the retraction of the publication “A β-lactamase based reporter system for ESX dependent protein translocation in mycobacteria” because the main conclusions of the publication are unreliable.
The main finding from the publication was the development of an ESX (precisely ESX-3) dependent protein translocation reporter based on an ampicillin resistant phenotype. Subsequent investigations by the authors have demonstrated that the reporter construct “pIV-blaTEM”, which was supposed to express the “Bla-TEM-EsxG” fusion protein, was accidentally replaced with a vector expressing a fusion protein carrying a twin-arginine-transporter (tat) secretion signal (not referenced in the publication). Re-testing of a newly constructed “true” BlaTEM-EsxG reporter strain indicated that the vector pIV-blaTEM does not confer an ampicillin-resistance phenotype. The second ESX reporter construct (pVI-blaTEM) expressing BlaTEM-EsxB does confer an ampicillin-resistance phenotype, but this phenotype does not depend on a functional ESX-1 secretion system as demonstrated by characterization of a subsequently generated eccD1 (MSMEG_0068) deletion mutant expressing BlaTEM-EsxB.
That’s about as straightforward an explanation as readers might wish for in such cases. Kudos to the researchers for their transparent handling of the problem, and for correcting the scientific record swiftly.