GENETICS Retraction for “Gentamicin B1 is a minor gentamicin component with major nonsense mutation suppression activity,” by Alireza Baradaran-Heravi, Jürgen Niesser, Aruna D. Balgi, Kunho Choi, Carla Zimmerman, Andrew P. South, Hilary J. Anderson, Natalie C. Strynadka, Marcel B. Bally, and Michel Roberge, which was first published March 13, 2017; 10.1073/pnas.1620982114 (Proc Natl Acad Sci USA 114:3479–3484).
The authors wish to note the following: “We have now determined that the gentamicin B1 compound we acquired commercially and used in our study was not gentamicin B1 but the closely related aminoglycoside G418. At the time we carried out the work, the only commercial source for gentamicin B1 was MicroCombiChem. The company provided two batches of compound, purified from gentamicin sulfate complex c, with certificates of analysis verifying the compound to be >97% pure gentamicin B1, together with HPLC-MS and NMR analysis showing the data conformed to gentamicin B1. Moreover, we asked a third party to carry out independent NMR analysis and they determined that the MicroCombiChem compound had a nitrogen in the vicinity of a methyl group, which is the case for gentamicin B1 but not for G418.
“In July 2018, while carrying out structure–activity relationship studies, we observed that a newly synthesized aminoglycoside derivative containing ring 1 of gentamicin B1 unexpectedly lacked nonsense suppression activity. This finding made us suspect the nature of the compound purchased from MicroCombiChem. At this time, gentamicin B1 became available from a second commercial source—Toronto Research Chemicals. Chemistry collaborators David Powell, David Williams, and Raymond Andersen graciously agreed to carry out NMR analysis of G418 disulfate salt from Sigma, gentamicin B1 free base from MicroCombiChem and gentamicin B1 diacetate salt from Toronto Research Chemicals. They determined that gentamicin B1 provided by MicroCombiChem was G418 whereas gentamicin B1 provided by Toronto Research Chemicals was composed principally (>95%) of gentamicin B1.
“We note that gentamicin B1 and G418 are closely related compounds, having the same atomic composition and molecular mass but differ in the location of amine and hydroxyl functionalities in ring 1. Ascertaining the structure of gentamicin B1 and identifying the NMR signals that distinguish it from G418 was not a trivial task because there are no published NMR data for gentamicin B1, and it was observed that the resonances of methylene protons vicinal to amino nitrogens in G418 and gentamicin B1 shifted considerably depending on pH and solvent. This could have led to the misidentification of G418 as gentamicin B1. Details of the NMR and biological analyses have been deposited in bioRxiv.
“All biological data presented in the PNAS paper (Figs. 1, 3, and 4, and Figs. S1, S3, S4, and S5) are accurate except that the results attributed to gentamicin B1 should now be considered to pertain to G418. We wish to apologize to the scientific community for any adverse consequences that may have resulted from following our work. Accordingly, we hereby retract the article.”