Figure 7.

Model of alginate O-acetylation machinery. AlgI receives an acetyl group from an as-yet unknown donor in the cytoplasm and the acetate group is passed through the inner membrane and transferred to AlgJ. AlgF mediates interactions in the periplasm allowing for the acetate to be passed from AlgJ to AlgX, where AlgX O-acetylates the newly polymerized mannuronic acid. OM, PG, IM denote the outer membrane, peptidoglycan, and inner membrane, respectively. Orange arrow indicates how the acetyl group is transferred between AlgI, AlgJ, and AlgX.