Practice question

Escherichia coli DNA polymerases IV encoded by dinB and V encoded by umuD'2C belong to Y-family of translesion polymerases, distinct from canonical A-family, B-family replicases, and X-family repair enzymes. Y-family members share unique structural features including little finger domain, unusually open solvent-accessible active site that accommodates bulky lesions such as benzo[a]pyrene adducts and thymine dimers, and absence of proofreading domain. They display low processivity, synthesizing only few nucleotides per binding event. Evolutionary conservation includes human Pol eta, iota, kappa. This classification explains low fidelity and lesion bypass specialization.