Fig. 2: Catalytic residues involved in the basal GTPase activity of TgMcrB.
From: Structural asymmetry governs the assembly and GTPase activity of McrBC restriction complexes
a, b Close-up views of the GTP-binding site at the tight D/E interface, highlighting residues involved in cis interactions, in particular those of the Walker A and B motifs, and the NxxD motif (a), and residues involved in trans interactions, in particular those of the Sensor II/arginine finger (SII/RF) motif (b). Spheres indicate waters (red) and a magnesium ion (green). Dashed lines indicate hydrogen bonds (black) and metal coordination (blue). c Sequence alignment of McrB homologs for the classic Walker A and B motifs, and the SII/RF motif. Arrows indicate the catalytic residues. Sequence alignment abbreviations are as follows: Tg Thermococcus gammatolerans, Ec Escherichia coli, Cj Campylobacter jejuni, Sa Staphylococcus aureus, Ab Aciduliprofundum boonei, Bc Bacillus cereus, Ss Streptococcus suis, Bp Butyrivibrio proteoclasticus, Ah Anaerobutyricum hallii. d Basal GTPase activity of wild-type TgMcrB and alanine mutants at the residues shown in a and b (n = 3, mean ± standard deviation). e Selected micrograph areas of negatively stained wild-type and mutant TgMcrBAAA incubated with GTPγS. Scale bars are 50 nm.
