Nature Microbiology 1, 16192 (2016); published 27 September 2016; corrected 7 November 2016

In Fig. 1a of the original version of this News and Views, it was not clear that the periplasmic flagellum attaches to the protoplasmic cylinder at a single cell pole. The figure caption has now been updated in all versions of the News and Views to make this point more clear. We apologize for any confusion this may have caused.