We previously have mapped N6-methyladenosine (m6A) sites within the genomic RNA 
of Rous sarcoma virus (RSV). The results of that study and of experiments using 
inhibitors of methylation suggest that m6A might be involved in mRNA processing 
events. We describe an approach for directly analyzing the function of m6A in 
RNA and for studying the sequence specificity of the m6A methylase. Two sites of 
methylation in RSV (nucleotides 7414 and 7424) were altered by 
oligonucleotide-directed mutagenesis. The highly conserved GAC consensus 
sequence at those sites was changed to GAU. The new sequences were no longer 
methylated in the RSV genomic RNA; the GAC sequence was required for efficient 
base modification at those two adenosines. The altered m6A pattern did not 
affect viral RNA processing or the viral life cycle within infected cells.