The structure of the Thermococcus gammatolerans McrB N-terminal domain reveals a new mode of substrate recognition and specificity among McrB homologs.

ABSTRACT: McrBC is a two-component, modification-dependent restriction system that cleaves foreign DNA-containing methylated cytosines. Previous crystallographic studies have shown that Escherichia coli McrB uses a base-flipping mechanism to recognize these modified substrates with high affinity. The side chains stabilizing both the flipped base and the distorted duplex are poorly conserved among McrB homologs, suggesting that other mechanisms may exist for binding modified DNA. Here we present the structures of the Thermococcus gammatolerans McrB DNA-binding domain (TgΔ185) both alone and in complex with a methylated DNA substrate at 1.68 and 2.27 Å resolution, respectively. The structures reveal that TgΔ185 consists of a YT521-B homology (YTH) domain, which is commonly found in eukar

SUBMITTER: Hosford CJ 

PROVIDER: S-EPMC6970917 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature