FIGURE 2.

The S88L mutation in EcTrmD. A, sequence alignment of the region in TrmD harboring S88L. The annotation is as follows: E. coli (YP_490830), Enterobacter cloacae (YP_004953267), Haemophilus influenzae (NP_438371), Helicobacter pylori (NP_207939), Pseudomonas aeruginosa (NP_252432), Salmonella enterica (NP_461604), B. subtilis (ZP_03591325), Clostridium botulinum (YP_001254944), Enterococcus faecalis (ZP_07107430), Mycobacterium tuberculosis (YP_005309161), Staphylococcus aureus (YP_040627), and Streptococcus pneumoniae (YP_816173). The alignment was generated using the ClustalW program (38). B, the position of S88 in the binary crystal structure of EcTrmD in complex with AdoHcy, showing secondary structural elements β4, α4, β5, α5, and β6 that form the trefoil knot fold (Protein Data Bank code 1P9P). The fold is localized in the N-terminal domain of TrmD, which is connected to the C-terminal domain via an invisible flexible linker.