That's the Way You Do It.

About one-third of the proteins encoded by the bacterial genomes that have been sequenced to date are proteins of "unknown function." Studies aimed at defining the biological functions of these proteins represent an important frontier in prokaryotic biology. The study presented by J. Herrou et al. (J Bacteriol 201:e00134-19, 2019) in this issue of the Journal of Bacteriology provides an excellent example of how to pursue such studies and define a new virulence determinant for an important zoonotic pathogen.