Structure-based sequence alignment of the KsgA alleles from E. coli (NP_414593), A. thaliana (NP_171690 i.e. PFC1), C. trachomatis L2 (YP_001654684 i.e. CTL0608), C. trachomatis L2 ksgAE9 , C. psittaci 6BC (GQ284731) and Candidatus Protochlamydia amoebophila UWE25 (YP_007394 i.e. pc0395). The alignment was generated using the Tcoffee expresso Web server using the structure of E. coli KsgA (PDB ID 1QRYR). Identical residues are denoted with an asterisk and strongly conserved residues with a colon; weakly conserved residues are marked with a period. Double-headed arrows indicate structural or catalytic motifs (I to VIII) common to S-adenosylmethionine-dependant methyltransferases and a dotted line indicates the C-terminal domain of E. coli KsgA . Shading shows change in amino acid sequence in KsgAL2ksgAE9 resulting from frameship up to stop codon and truncation.