Nature 444, 221–225 (2006); doi:10.1038/nature05258

This Letter is retracted by Nature. This follows an investigation by the University of Alabama at Birmingham, Alabama, USA, of structures deposited into the Protein Data Bank under accession 2HR0 by H. M. Krishna Murthy. Co-authors who agree with the Retraction: A. Abdul Ajees, John E. Volanakis, Sthanam V. Narayana. Co-authors who do not support the Retraction: Girish J. Kotwal and H. M. Krishna Murthy. K. Gunasekaran has not responded. The report from the University of Alabama at Birmingham investigation is available at: http://www.uab.edu/reporterarchive/71570-uab-statement-on-protein-data-bank-issues.