Specifically methylates the guanine in position 2445 (m2G2445) and the guanine in position 2069 (m7G2069) of 23S rRNA. Methylation occurs before assembly of 23S rRNA into 50S subunits. guanosine(2445) in 23S rRNA + S-adenosyl-L-methionine = H(+) + N(2)-methylguanosine(2445) in 23S rRNA + S-adenosyl-L-homocysteine guanosine(2069) in 23S rRNA + S-adenosyl-L-methionine = H(+) + N(2)-methylguanosine(2069) in 23S rRNA + S-adenosyl-L-homocysteine The N-terminal RlmL activity is enhanced by the C-terminal RlmK activity. Monomer. Consists of a N-terminal RlmL domain and a C-terminal RlmK domain, linked by a highly flexible loop. Belongs to the methyltransferase superfamily. RlmKL family.