Table 4.

Comparison of modifications and their sequence locations between L. lactis, B. subtilis and E. coli

Modification	L. lactis	B. subtilis	E. coli	Comments
D	✓	✓	✓	Universally conserved in bacteria – found at U20
ψ	✓	✓	✓	Universally conserved in bacteria – found at U55
xm5s2U	✓ (x=cmn)	✓ (x=cmn)	✓ (x=mn)	Usually found at U34 in tRNAs that decode codons ending in G or A
s4U	✓*	✓	✓	*Not found in total nucleoside analysis but identified in RNA modification mapping studies
Cm	✓	✓	✓	Found at C34 of Leu-tRNACAA
m5U	✓	✓	✓	Universally conserved in bacteria – found at U54
I	✓	✓	✓	Found at A34 of Arg-tRNAACG
xo5U	✓ (x=m)	✓ (x=m)	✓ (x=cm)	Usually found at U34 in 4 or 6-box tRNAs (Ala, Pro, Ser, Thr, Val); 5-methoxy derivatives found in gram positive bacteria; 5-carboxy derivatives found in gram negative bacteria
m7G	✓	✓	✓	Universally conserved in bacteria – found at G46
m1G	✓	✓	✓	Usually found at G37 in tRNAs-Pro, Arg, Leu
ac4C	✓	✓	✓	Found at C34 of Met-tRNACAU
t6A	✓	✓	✓	Universally conserved in bacteria – found at A37 of tRNAs decoding codons beginning with A.
m2A	✓	✓	✓
m6A	✓	✓	✓	Universally conserved in bacteria – found at A37
i6A	✓	✓	✓	Highly conserved in bacteria – found at A37 of tRNAs decoding codons beginning with U.
m1A	✓	✓	✓	Highly conserved in bacteria although not seen in E. coli – found at A58
ms2t6A	✓	✓	[m6t6A]	Commonly identified in bacteria – found at A37