FIG 2.

NpmA methylates G and A at nucleotide 1408 at the same position (N1). (A) RT analysis of (left to right) unmodified 16S rRNA (16S), NpmA or KamB in vitro-modified 16S rRNA extracted from Δ7prrn-A1408G 30S subunits with and without subsequent sodium borohydride treatment, and equivalent analysis of in vivo-modified 16S rRNA from wild-type E. coli BL21(DE3) cells expressing the m⁷G1405 methyltransferase Sgm. The values below the gel are fold enhancement with NaBH₄ treatment (+). (B and C) TLC analysis of the nucleoside composition of the 16S rRNA fragment corresponding to nucleotides 1378 to 1432 from unmodified wild-type (B) and NpmA-modified Δ7prrn-A1408G (C) 30S subunits. Regions boxed with a dotted line are duplicated in the insets (solid lines) with 20×-increased contrast to allow visualization of the low-abundance modified nucleotides.