Conserved residues important for Rap proteins known to interact with Spo0F or ComA are not conserved in Rap_LS20.

Alignment of the N-terminal regions of Bacillus Rap proteins. In addition to RapLS20 and Rap576, the alignment includes Rap proteins that previously have been demonstrated to dephosphorylate Spo0F (RapP, RapA, RapB, RapE, RapI, RapJ RapH, RapXO1 ( = BXA0205), and Rap60 [Spo0F-phosphatase activity has not been demonstrated biochemically for Rap60]), and those shown to interact with ComA (RapF, RapC and RapH). Regions adapting an α-helical formation in RapH are indicated with green cylinders above the alignment. The highly conserved tryptophan residue present in all these Rap proteins is indicated in green. The catalytic Gln47 residue of RapH that is conserved in six of the seven other Spo0F-interacting Rap proteins as well as in RapI is highlighted in red. Alanine substitutions in Rap proteins that cause complete or significant loss of function/interaction with Spo0F and ComA are highlighted by blue boxes [44], [45]. RapH residue Leu55 is conserved in RapLS20 and Rap576. It is worth mentioning that although the L55A mutant affected the function of RapH in vivo, no loss of RapH function was observed for this mutant in vitro [44]. Positions of the α-helices are indicated above the alignment.