Catalyzes the transfer of an acetyl residue from acetyl-CoA onto GDP-perosamine to form GDP-N-acetyl-perosamine. acetyl-CoA + GDP-alpha-D-perosamine = CoA + GDP-N-acetyl-alpha-D-perosamine + H(+) Optimum pH is 8.5. Bacterial outer membrane biogenesis; LPS O-antigen biosynthesis. Homotrimer. Belongs to the transferase hexapeptide repeat family.