poliota-dependent lesion bypass in vitro.
Based upon phylogenetic relationships, the broad Y-family of DNA polymerases can be divided into various subfamilies consisting of UmuC (polV)-like; DinB (polIV/polkappa)-like; Rev1-like, Rad30A (poleta)-like and Rad30B (poliota)-like polymerases. The polIV/polkappa-like polymerases are most ubiquitous, having been identified in bacteria, archaea and eukaryotes. In contrast, the polV-like polymerases appear restricted to bacteria (both Gram positive and Gram negative). Rev1 and poleta-like polymerases are found exclusively in eukaryotes, and to date, poliota-like polymerases have only been identified in higher eukaryotes. In general, the in vitro properties of polymerases characterized within each sub-family are quite similar. An exception to this rule occurs with the poliota-like polymerases, where the enzymatic properties of Drosophila melanogaster poliota are more similar to that of Saccharomyces cerevisiae and human poleta than to the related human poliota. For example, like poleta, Drosophila poliota can bypass a cis-syn thymine-thymine dimer both accurately and efficiently, while human poliota bypasses the same lesion inefficiently and with low-fidelity. Even in cases where human poliota can efficiently insert a base opposite a lesion (such as a synthetic abasic site, the 3'T of a 6-4-thymine-thymine pyrimidine-pyrimidone photoproduct or opposite benzo[a]pyrene diol epoxide deoxyadenosine adducts), further extension is often limited. Thus, although poliota most likely arose from a genetic duplication of poleta millions of years ago as eukaryotes evolved, it would appear that poliota from humans (and possibly all mammals) has been further subjected to evolutionary pressures that have "tailored" its enzymatic properties away from lesion bypass and towards other function(s) specific for higher eukaryotes. The identification of such functions and the role that mammalian poliota plays in lesion bypass in vivo, should hopefully be forthcoming with the construction of human cell lines deleted for poliota and the identification of mice deficient in poliota.
Vaisman
Alexandra
A
Section on DNA Replication, Repair and Mutagenesis, National Institute of Child Health and Human Development, National Institutes of Health, Building 6, Room 1A13, 9000 Rockville Pike, Bethesda, MD 20892-2725, USA.
Frank
Ekaterina G
EG
McDonald
John P
JP
Tissier
Agnès
A
Woodgate
Roger
R
D000818:Animals; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008954:Models, Biological; D009154:Mutation; D010802:Phylogeny; D000094769:DNA Polymerase iota
D004259:DNA-Directed DNA Polymerase; D000094769:DNA Polymerase iota; C000722070:POLI protein, human