Corrections

MICROBIOLOGY. For the article ‘‘Kinetic analysis of a complete poxvirus transcriptome reveals an immediate-early class of genes,’’ by Erika Assarsson, Jason A. Greenbaum, Magnus Sundström, Lana Schaffer, Jennifer A. Hammond, Valerie Pasquetto, Carla Oseroff, R. Curtis Hendrickson, Elliot J. Lefkowitz, David C. Tscharke, John Sidney, Howard M. Grey, Steven R. Head, Bjoern Peters, and Alessandro Sette, which appeared in issue 6, February 12, 2008, of Proc Natl Acad Sci USA (105:2140–2145; first published February 1, 2008; 10.1073 pnas.0711573105), the authors note that in Fig. 2, the y axis appeared incorrectly. The scale on the y axis should be 0–200. The corrected figure and its legend appear below. BIOPHYSICS, CHEMISTRY. For the article ‘‘End-to-end distance distributions and intrachain diffusion constants in unfolded polypeptide chains indicate intramolecular hydrogen bond formation,’’ by Andreas Möglich, Karin Joder, and Thomas Kiefhaber, which appeared in issue 33, August 15, 2006, of Proc Natl Acad Sci USA (103:12394–12399; first published August 7, 2006; 10.1073 pnas.0604748103), the authors note the following: ‘‘The given values for the average end-to-end distances and the diffusion constants are too small because of a systematic error in the fluorescence decay fitting routine. The donor fluorescence intensity obtained by integration of Eq. 2 erroneously twice contained a term considering the 1/r6 distance dependence of FRET. Performing the integration as described in equation 14 of ref. 26 of our article yields an average end-to-end distance for the (Gly-Ser)16 model peptide of (38 1) Å in water. This distance increases to (50 1) Å in 8 M GdmCl, compared with an originally reported increase from 18.9 to 39.2 Å. The respective diffusion constants range from (49 2) 10 7 cm2 s 1 in water to (58 5) 10 7 cm2 s 1 in 8 M GdmCl.’’ These errors do not affect the conclusions of the article.