Nat. Chem. Biol. 8, 655–660 (2012); published online 10 June 2012; corrected after print 21 May 2013

In the version of this article initially published, Irina Krylova was inadvertently acknowledged rather than included in the author list. The author list, author contributions and acknowledgements have been edited to reflect this change. The text and Supplementary Methods have also been updated to more accurately describe phage clone and peptide optimization. The errors have been corrected in the HTML and PDF versions of the article.