Table 3.

Comparison of MtbEf-Tu and E. coli Ef-Tu

Enzymatic property	E. coli Ef-Tu	M. tuberculosis Ef-Tu
		MtbEf-Tuphos	MtbEf-Tuunphos
Interaction with GTP (Kd)	5 × 105 M−1 s−1 (±1 × 105) (time dependent)a	4.8 × 10−6 M (±0.698 × 10−6) (steady state)	1.6 × 10−6 M (±0.386 × 10−6) (steady state)
Interaction with GDP (rate of dissociation)	2 × 10−3 s−1 (±1 × 10−3)a	5.5 × 10−3 s−1 (±1.76 × 10−4)	2.07 × 10−3 s−1 (±0.86 × 10−4)
Effect of Ef-Ts
Dissociation of GDP	125 s−1 (±25)a	0.64 s−1 (±14.9 × 10−3)	0.53 s−1 (±0.707 × 10−3)
Phosphorylation of Ef-Tu	Enhances Ef-Tu phosphorylationb	No effect
Effect of kirromycin
Nucleotide binding	Stalls Ef-Tu in activated state; does not bind to phosphorylated Ef-Tub	Does not interact	Enhances interaction
Phosphorylation of Ef-Tu	Inhibits Ef-Tu phosphorylationb	No effect
Phosphorylated residue(s)	Thr382 (domain III)c	Thr9, Thr17, Thr29, Thr46, Thr64, Thr74, Thr118 (domain I), Thr227, Thr256, Thr259 (domain II), Thr337, Ser362 (domain III)
Effect of phosphorylation	Facilitates its release from the ribosome and prevents ternary complex formationb	Decreases affinity for guanine nucleotides (GTP and GDP)

^aSee reference 19.

^bSee reference 3.

^cSee reference 28.