In Escherichia coli, UV and many chemicals appear to cause mutagenesis by a process of translesion synthesis that requires DNA polymerase III and the SOS-regulated proteins umuC, umuD and recA. This machinery allow the replication to continue through DNA lesion, and therefore avoid lethal interruption of DNA replication after DNA damage [1].

Proteins known to contain an UmuC domain are listed below:

• Bacterial umuC protein.
• Escherichia coli mucB and Salmonella typhimurium impB proteins. Plasmid- born analogues of the UmuC protein.
• Salmonella typhimurium samB, a plasmid associated homologue of UmuC .
• Bacterial DNA polymerase IV.
• Yeast REV1 protein, required for normal induction of mutations by physical and chemical agents.

The profile we developed spans the complete UmuC domain.