This protein produces a dimethylation of the adenine residue at position 2085 in 23S rRNA, resulting in reduced affinity between ribosomes and macrolide-lincosamide-streptogramin B antibiotics. adenosine(2085) in 23S rRNA + 2 S-adenosyl-L-methionine = 2 H(+) + N(6)-dimethyladenosine(2085) in 23S rRNA + 2 S-adenosyl-L-homocysteine Belongs to the class I-like SAM-binding methyltransferase superfamily. rRNA adenine N(6)-methyltransferase family.