Mutant Uracil DNA glycosylase with improved thermal sensitivity

An isolated UDG (Uracil DNA Glycosylase) polypeptide from Escherichia coli consisting of the amino acid sequence set forth in SEQ ID NO:

• 1 having at least one amino acid substitution selected from the group consisting of E4A, W7A, E13A, Q16A, Y19A, D43X, F48A, F50A, E52A, H67A, K57A, Q71A, H73A, P87A, L96A, E112A, L121A, H134A, E142A, F144A, R156A, F161A, L162A, W164A, H180A, L183A, H202A, G214E, G214W, G214R, W220A, and L224A, in which the number indicates the position of the substituted amino acid and the amino acids are indicated as a single letter code and X indicates any amino acids, in which the codes on the left and right sides of the position indicate a wild type and substituted residues, respectively,
• wherein the UDG has an improved thermal sensitivity in comparison to a wild type UDG from E. coli,
• wherein the X of D43X is A, C, G, K, H, I, P, R, V or W.