Catalyzes the acetyl-CoA-dependent N-acetylation of aromatic amines, and, probably, the O-acetylation of N-hydroxyarylamines. In vitro, catalyzes the N-acetylation of various arylamines such as aminobenzoic acid, aminophenol, aminotoluene, phenetidine, anisidine, aniline, isoniazid and 2-amino-fluorene (PubMed:10806332, PubMed:23452042). N-hydroxyarylamine O-acetyltransferase activity has not been assayed directly, however, NhoA activity is required for the mutagenicity of nitroaromatic compounds, suggesting that it also has O-acetyltransferase activity (Probable). acetyl-CoA + an arylamine = an N-acetylarylamine + CoA acetyl-CoA + an N-hydroxyarylamine = an N-acetoxyarylamine + CoA Inhibited by salicylic acid, acetylsalicylic acid, 2,6-dichrolo-4-nitrophenol, N-ethylmaleimide and iodoacetamide. Optimum pH is 7.4. Optimum temperature is 37 degrees Celsius. Homodimer. Acetylated on Lys-214 and Lys-281. Deacetylated by CobB. Deletion mutants show marked resistance to nitro compound mutagenicity. Belongs to the arylamine N-acetyltransferase family.