Adenosine dimethyltransferase

Function

Adenosine dimethyltransferase (KsgA) dimethylates two adjacent adenines at the C-terminal of the 16S rRNA in the small 30S ribosomal subunit, thus modifying it. KsgA catalyzes the dimethylation of adenines 1518-1519 using S-adenosyl-methionine (SAM) as the methyl donor and producing S-adenosyl-homocysteine (SAH).

Relevance

KsgA confers resistance to the antibiotic kasugomycin.

Structural highlights

The active site pocket of KsgA in E, coli contains residues N113 and L114 which are part of motif IV SAM-dependent methyltrasferase sequence. The active site can acomodate both adenosine and methyladenosine.