Posttranslational Regulation of Human DNA Polymerase ?.

ABSTRACT: Human DNA polymerases (pols) ? and ? are Y-family DNA polymerase paralogs that facilitate translesion synthesis past damaged DNA. Both pol? and pol? can be monoubiquitinated in vivo. Pol? has been shown to be ubiquitinated at one primary site. When this site is unavailable, three nearby lysines may become ubiquitinated. In contrast, mass spectrometry analysis of monoubiquitinated pol? revealed that it is ubiquitinated at over 27 unique sites. Many of these sites are localized in different functional domains of the protein, including the catalytic polymerase domain, the proliferating cell nuclear antigen-interacting region, the Rev1-interacting region, and its ubiquitin binding motifs UBM1 and UBM2. Pol? monoubiquitination remains unchanged after cells are exposed to DNA-damaging agents such as UV light (generating UV photoproducts), ethyl methanesulfonate (generating alkylation damage), mitomycin C (generating interstrand cross-links), or potassium bromate (generating direct oxidative DNA damage). However, when exposed to naphthoquinones, such as menadione and plumbagin, which cause indirect oxidative damage through mitochondrial dysfunction, pol? becomes transiently polyubiquitinated via Lys(11)- and Lys(48)-linked chains of ubiquitin and subsequently targeted for degradation. Polyubiquitination does not occur as a direct result of the perturbation of the redox cycle as no polyubiquitination was observed after treatment with rotenone or antimycin A, which both inhibit mitochondrial electron transport. Interestingly, polyubiquitination was observed after the inhibition of the lysine acetyltransferase KATB3/p300. We hypothesize that the formation of polyubiquitination chains attached to pol? occurs via the interplay between lysine acetylation and ubiquitination of ubiquitin itself at Lys(11) and Lys(48) rather than oxidative damage per se.

SUBMITTER: McIntyre J 

PROVIDER: S-EPMC4646365 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature