Comparison of nucleotide sequences at the active sites in each acyltransferase (AT) domain. (A) Sequence alignment of each domain by ClustalW. (B) Phylogenic dendrogram of each domain. The first AT domain in module 1 (AT1) was highly similar with AT domains specific for dimethylmalonyl-CoA to incorporate isobutyl group. Two AT domains of module 3 (AT3) and module 7 (AT7) was highly homologous with other AT domains specific for malonyl-CoA to incorporate acetyl group. The other nine AT domains exhibited the similar sequences with other AT domains specific for methylmalonyl-CoA to incorporate propionyl group. Contrastly, AT domains of module 6 (AT6) and module 12 (AT12) shows high similarity with AT domains specific for methylmalonyl-CoA, but they were assumed to be specific for methoxymalonyl-CoA to incorporate methoxyacetyl group, based on the chemical structure of bafilomycin.