FIGURE 1.

A, ligase-catalyzed biotin transfer occurs in two steps in which an activated biotin intermediate is first synthesized from biotin and ATP with the release of pyrophosphate, and the biotin moiety of bio-5′-AMP is then covalently attached to a specific lysine residue on BCCP. B, alignment (33) of the E. coli, H. sapiens, and P. horikoshii BPL catalytic domain sequences. The identities (black) and similarities (gray) are highlighted. The N-terminal domains of the E. coli and H. sapiens sequences are not shown.