Acetylates the N-terminal alanine of ribosomal protein S18 (PubMed:6991870, PubMed:2828880). Also acts as a N-epsilon-lysine acetyltransferase that catalyzes acetylation of several proteins (PubMed:30352934). acetyl-CoA + N-terminal L-alanyl-[ribosomal protein bS18] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-alanyl-[ribosomal protein bS18] acetyl-CoA + L-lysyl-[protein] = CoA + H(+) + N(6)-acetyl-L-lysyl-[protein] Mutation of the gene impairs the acetylation of the N-terminal alanine of ribosomal protein S18, but does not affect acetylation of ribosomal proteins S5 and L12. Belongs to the acetyltransferase family. RimI subfamily.