FIG 5.

Sequence alignment of the Mmp10 homologs. Mmp10 homologs from six genomes representing each methanogen order and one ANME-2 genome were aligned to illustrate conserved motifs. At the N terminus, conserved motifs predicted to bind SAM are highlighted in purple, including CXXXCXXC, GGD, and GXTXGXGXXXXE/D. In fact, many of the x residues in the CXXXCXXC and GXTXGXGXXXXE/D motifs are highly conserved, but they are labeled in such a way to highlight just the residues conserved in other SAM binding proteins. Nevertheless, these conserved x residues may also play important roles. Near the CXXXCXXC motif, there are also two conserved CXXC motifs, highlighted in red, that may bind Fe-S clusters. In the middle region of Mmp10, residues highlighted in green form a conserved D-29X-N-D-35X-N-30X-R motif that may bind CH₃-H₄MPT, a potential methyl donor for SAM. At the C terminus, a conserved H residue is highlighted in brown (see the text).