Abstract
In our article (3), we argue that formation of BeF complexes with receiver domains leads to conformational changes that mimic phosphorylation. In the opposing article, Varughese (2) argues that this might not be the case for Spo0F. As with any structure, the model produced should generate ideas for further experiments to test specific aspects of the interpretation. The functional equivalence of BeF complex formation and phosphorylation does remain to be directly tested for Spo0F; solving a crystal structure of the BeF complex of 3 Spo0F with Spo0B might be a good test.