In this Letter, author Ana C. Puhl was inadvertently omitted from the list of authors, with affiliation: Platform Technology & Science, GlaxoSmithKline, Collegeville, PA, USA. At the time this research was initiated, Ana C. Puhl held a post-doctoral position at GlaxoSmithKline through a fellowship awarded from the Brazilian government (the ‘Science without Borders’ programme), and the GlaxoSmithKline ‘Trust in Science’ programme. She performed crystallization trials and was instrumental in the determination of the structure of compounds 1 and 2 described in Figs. 1 and 2. In the ‘Author contributions’ section, the relevant sentence should read: “N.C. performed HDX studies and determined X-ray structures with assistance from L.W. and A.C.P.”. The Letter has been corrected online.