SMUG1 Protein, Human (His-SUMO)

The SMUG1 protein serves as a pivotal factor in base excision DNA repair, specifically recognizing and initiating repair processes for base lesions in the genome. Functioning as a monofunctional DNA glycosylase, SMUG1 displays specificity for uracil (U) residues in DNA, with a notable preference for single-stranded DNA substrates. Its enzymatic activity is more pronounced toward mismatches (U/G) compared to matches (U/A). SMUG1 exhibits the capability to excise not only uracil (U) but also 5-formyluracil (fU), and uracil derivatives with oxidized groups at C5, such as 5-hydroxyuracil (hoU) and 5-hydroxymethyluracil (hmU), in both single-stranded (ssDNA) and double-stranded DNA (dsDNA). Importantly, this DNA glycosylase does not act on analogous cytosine derivatives (5-hydroxycytosine and 5-formylcytosine), nor other oxidized bases. SMUG1's activity is damage-specific and exhibits dependence on salt concentration, with a substrate preference hierarchy of ssDNA > dsDNA (G pair) = dsDNA (A pair) under low salt conditions, and dsDNA (G pair) > dsDNA (A pair) > ssDNA under high salt concentrations.