1. Two nucleotide-binding sites of ABCE1 act functionally asymmetric.
Two nucleotide-binding sites of ABCE1 act functionally asymmetric. (A) Overall structure of ABCE1 without the FeS cluster domain (PDB 3OZX) and zoom into the two catalytic sites. Catalytic glutamates (E238, magenta, in site I; and E485, cyan, in site II) are located between Walker B and D-loop motifs. The ABC-signature motif approaches bound nucleotides from the opposing NBD and contains S214 (cyan, in site II) and S461 (magenta, in site I). (B) Strategic substitutions in ABCE1 prevent ATP hydrolysis or occlusion in the respective sites. (C) Asymmetric ATPase activity of ABCE1 mutants. Mean ± SD, n = 3. (D) Hydrolysis of 32P-γ-ATP (5 mM) by ABCE1 (1 μM) at 70°C. Representative set of three independent experiments. (E) Yeast plasmid shuffling assay illustrates the significance of an intact control site II. Only WT and ABCE1E247A (site I) remain viable (+), ABCE1E247Q (site I) shows a strong growth defect (–), whereas all other mutations are lethal (–). Representative set of two independent experiments.
Elina Nürenberg-Goloub et al. LSA 2018;1:e
© 2018 Nürenberg-Goloub et al.