Fig 3. The interchanged regions for the investigation of C2/C8 specificity.

(A) Alignment of the amino acid sequences of Cfr (GI: 34328031 / NCBI: NP_899167.1) and RlmN (GI: 16130442 / NCBI: NP_417012.1). The seven coloured boxes depict the regions that encompass the active site of the enzymes. The dots above the sequence indicate the CX₃CX₂C motif. The black arrow shows the cysteine 338/355. The grey shading mark the 13 selectively conserved positions in Cfr- or RlmN-like proteins. (B) Representation of the X-ray crystal structure of RlmN (PDB file 3RFA) [26] with the same region colouring as in the amino acid alignment and oriented similar to the Cfr model structure in Fig 2A. Also, the SAM molecule and the [4Fe-4S] cluster are included as in Fig 1A. The three cysteines in the CX₃CX₂C as well as the Cys355 are shown in green sticks.