Fig. 2: Structural interplay between the [4Fe-4S] cluster and active site.

A Structural composition of the catalytic pocket and proximity to the [4Fe-4S] cluster. The catalytic pocket comprises 4 α-helixes (H1-H4) and a Helix-Helix (H-H) connector. The H-H connector links the α-helix H3 with an α-helix, which is part of both the catalytic pocket, where Asn238 resides, and the [4Fe-4S] cluster. Catalytic Glu134 and Asp236 reside within the α-helix H2 and the H-H connector, respectively. B Mutual evolutionary relationships show a strong coevolutionary signal among the different structural components of the catalytic pocket and the [4Fe-4S] cluster motif of MUTYH/MutY proteins. Mutual Information (MI) detects positions within a multiple sequence alignment that are co-evolving to reveal evolutionary constraints imposed by structure or function. The protein sequence is presented as a circular plot, residue by residue. The different components taken into account by the coevolutionary analysis such as conservation, cumulative mutual information (MI), proximity MI, and MI pairs are depicted in the figure. C Residues implied in the structural connectivity between the [4Fe-4S] cluster and the active site. The H-bond network establishing this connectivity is shown in cyan dotted lines. The simulated annealing composite omit (gray) and anomalous difference (orange) maps were contoured at 1.1- and 6-sigma, respectively. D Disruption of the structural connectivity between the [4Fe-4S] cluster and the active site in the R149Q GsMutY-THF:OG crystal structure. This mutation shows alternative conformations for the [4Fe-4S] cluster with a displacement of 1.4 Å along with two different conformers of Cys 198. R149Q is the analogous R241Q mutation in MUTYH. The simulated annealing composite omit map (gray) was calculated to the 1.51 Å resolution limit and contoured at 1.0-sigma. E Conservation of the residues involved in the [4Fe-4S] cluster-active site structural connectivity among Helix-hairpin-Helix (HhH) DNA glycosylases that also contain the iron-sulfur cofactor (MUTYH/MutY, MIG and EndoIII).