Sequence analysis of SssF. (A) Primary structure of the S. saprophyticus MS1146 SssF protein. The putative signal peptide, the corresponding gene region used for PCR screening, the region used in the multiple alignment (Additional file 2: Figure S1), the region used for polyclonal antibody raising and the LPDTG sortase anchor motif are indicated. (B) Structural prediction of the mature form of SssF. Residues coloured in red and in blue are predicted to adopt α-helical and β-strand conformations respectively. (C) Crystal structures of tropomyosin and alpha-actinin identified as likely structurally similar to SssF.