A member of the E2/UBC superfamily of proteins found in several bacteria. The active site residues are similar to the eukaryotic E2 proteins but lack the conserved asparagine. Members of this family are usually fused to an E1 domain at the C-terminus. The protein is usually in the gene neighborhood of a gene encoding a member of the pol-beta nucleotidyltransferase superfamily. Many of the operons in this family are in ICE-like mobile elements and plasmids.