Together with AlgI and AlgJ, forms an inner membrane complex which probably interacts with the alginate polymerization-transport complex and adds acetyl groups at the O-2 and O-3 positions of mannuronate residues. Acetylation of alginate is important for the architecture of biofilms and increases resistance to opsonic killing in the host.
Also known as Alginate biosynthesis protein AlgX (Probable alginate O-acetyltransferase AlgX). Plays two roles in the biosynthesis of the exopolysaccharide alginate: protects alginate from degradation as the polymer traverses the periplasm, and also plays a role in its O-acetylation. Acetylation of alginate causes the cells in the biofilm to adhere better to lung epithelium, form microcolonies, and resist the effects of the host immune system and/or antibiotics. Displays a low acetylesterase activity in vitro using a pseudosubstrate, 3-carboxyumbelliferyl acetate. Probably has acetyltransferase activity in vivo.