Table 1.

Binding of TrmA wild-type and variants to tRNA^Phe in the presence and absence of SAM. The dissociation constants (K_D) and standard deviations were determined in triplicate by nitrocellulose filter binding (Figure 2, Supplementary Figure S1).

TrmA variant	K D, μM
	[3H]-tRNA	[3H]-tRNA + SAM
Wild-type (wt)	0.02 ± 0.01a	0.66 ± 0.11
C324A	1.08 ± 0.16	0.03 ± 0.02a
E358Q	0.07 ± 0.04a	0.011 ± 0.007
Q190A	0.28 ± 0.10	1.5 ± 0.2
G220D	0.22 ± 0.05	0.06 ± 0.03
R51A	0.14 ± 0.07	1.15 ± 0.34
R51A C324A	2.8 ± 0.7	0.16 ± 0.06
F106A	1.0 ± 0.4	2 ± 1
F106A C324A	18 ± 7	6 ± 2
H125A	4 ± 3	6 ± 2
H125A C324A	47 ± 27	3 ± 1
F106E	1.6 ± 0.9	3.2 ± 1.0
H125E	1.4 ± 0.4	2.1 ± 0.8

^aNote that K_Ds in the very low nanomolar range have not been determined with high accuracy as very few data points are found in this region of the binding curve.