Human and mouse homologs of Escherichia coli DinB (DNA polymerase IV), members of the UmuC/DinB superfamily

understand the mechanisms underlying mutagenesis in eukaryotes better, we h ave cloned mouse and human homologs of the Escherichia coli dinB gene. E, c oli dinB encodes DNA polymerase IV and greatly increases spontaneous mutati ons when overexpressed, The mouse and human DinB1 amino acid sequences shar e significant identity with E. coli DinB, including distinct motifs implica ted in catalysis, suggesting conservation of the polymerase function. These proteins are members of a large superfamily of DNA damage-bypass replicati on proteins, including the E. coli proteins UmuC and DinB and the Saccharom yces cerevisiae proteins Rev1 and Rad30, In a phylogenetic Free, the mouse and human DinB1 proteins specifically group with E. coli DinB, suggesting a mitochondrial origin for these genes. The human DINB1 gene is localized to chromosome 5q13 and is widely expressed.