O6-methylguanine-DNA alkyltransferase; Involved in the cellular defense against the biological effects of O6-methylguanine (O6-MeG) and O4-methylthymine (O4-MeT) in DNA. Repairs the methylated nucleobase in DNA by stoichiometrically transferring the methyl group to a cysteine residue in the enzyme. This is a suicide reaction: the enzyme is irreversibly inactivated.

DNA polymerase I; In addition to polymerase activity, this DNA polymerase exhibits 5'-3' exonuclease activity.

Small acid-soluble spore protein (minor alpha/beta-type SASP); BH1750.

DNA polymerase IV 1; Poorly processive, error-prone DNA polymerase involved in untargeted mutagenesis. Copies undamaged DNA at stalled replication forks, which arise in vivo from mismatched or misaligned primer ends. These misaligned primers can be extended by PolIV. Exhibits no 3'-5' exonuclease (proofreading) activity. May be involved in translesional synthesis, in conjunction with the beta clamp from PolIII (By similarity).

Endonuclease IV; Endonuclease IV plays a role in DNA repair. It cleaves phosphodiester bonds at apurinic or apyrimidinic (AP) sites, generating a 3'-hydroxyl group and a 5'-terminal sugar phosphate.

methylphosphotriester-DNA alkyltransferase (AraC/XylS family); BH0394.

Multifunctional protein involved in homologous recombination; Can catalyze the hydrolysis of ATP in the presence of single- stranded DNA, the ATP-dependent uptake of single-stranded DNA by duplex DNA, and the ATP-dependent hybridization of homologous single-stranded DNAs. It interacts with LexA causing its activation and leading to its autocatalytic cleavage; Belongs to the RecA family.

Endonuclease III (DNA repair); DNA repair enzyme that has both DNA N-glycosylase activity and AP-lyase activity. The DNA N-glycosylase activity releases various damaged pyrimidines from DNA by cleaving the N-glycosidic bond, leaving an AP (apurinic/apyrimidinic) site. The AP-lyase activity cleaves the phosphodiester bond 3' to the AP site by a beta-elimination, leaving a 3'-terminal unsaturated sugar and a product with a terminal 5'- phosphate.

Biotin synthase; Catalyzes the conversion of dethiobiotin (DTB) to biotin by the insertion of a sulfur atom into dethiobiotin via a radical-based mechanism; Belongs to the radical SAM superfamily. Biotin synthase family.