Volume 449 (2013), pp. 631–642

In the Author Contribution section, the author Michaela Faulstich (not Vera Kozjak-Pavlovic and Michaela Fraunholz) should have been acknowledged as having sole responsibility for carrying out the site-directed mutagenesis and invasion assays. In addition, the PorB purification work should have been attributed to the author Vera Kozjak-Pavlovic (not Vera Kozjak).