Alignment of conserved motifs I-IV of GH70 family enzymes.

(A) (putative) GtfD-like 4,6-α-GTase enzymes, (B) (putative) GtfC-like 4,6-α-GTase enzymes, (C) (putative) GtfB-like enzymes, and (D) sucrose-active enzymes. The seven strictly conserved amino acid residues in GH70 enzymes (numbered 1 to 7 above the sequences) are also conserved in GtfD-like proteins. Amino acids that constitute the catalytic triad are highlighted in bold and lightly shaded. Residues forming acceptor subsites -1, +1 and +2 in Gtf180-ΔN [7] are indicated in green, red and blue, respectively. Abbreviations at the bottom: NU = nucleophile, A/B = general acid/base, TS = transition state stabilizer. a The protein sequences are annotated by their GenBank Accession number, except for the Burkholderia sp. NFACC38-1 GtfD-like protein sequence that is labeled with its IMG/ER Gene.