Both in yeast and humans, DNA polymerase (Pol) functions in the error-free replication of UV-damaged DNA, and Pol has the unique ability to efficiently replicate through a cis-syn thymine– thymine (T–T) dimer by inserting two As opposite the two Ts of the dimer. Although human DINB1-encoded Pol belongs to the same protein family as Pol , Pol shows no ability to bypass this DNA lesion and its bi...

Saccharomyces cerevisiae DNA polymerase delta (Pol delta) and DNA polymerase epsilon (Pol epsilon) are replicative DNA polymerases at the replication fork. Both enzymes are stimulated by PCNA, although to different levels. To understand why and to explore the interaction with PCNA, we compared Pol delta and Pol epsilon in physical interactions with PCNA and nucleic acids (with or without RPA), ...

Background: DNA polymerase β (pol β) is a key enzyme of base excision repair pathway. It is a 1-kb gene consisting of 14 exons. Its catalytic part lies between exon 8 and exon 14. Exon 12 has a role in deoxyribonucleotide triphosphate selection for nucleotide transferase activity. Methods: Genomic DNA was isolated from ovarian carcinoma samples. Single strand conformation polymorphism...

Eukaryotes require 3 DNA polymerases for normal replisome operations, DNA polymerases (Pol) α, delta and epsilon. Recent biochemical and structural studies support the asymmetric use of these polymerases on the leading and lagging strands. Pol epsilon interacts with the 11-subunit CMG helicase, forming a 15-protein leading strand complex that acts processively in leading strand synthesis in vit...

We have studied the biosynthesis of avian retrovirus proteins related to reverse transcriptase in permissive avian embryonic cells. Analysis of immune precipitates from avian sarcoma virus (ASV)-infected cells demonstrated the presence of the 180,000-dalton gag-pol "read-through" protein (Pr180gag-pol) and a 130,000-dalton polypeptide (Pr130gag-pol). Pr130gag-pol was found, in serological and p...

Recent studies of the three eukaryotic transcription machineries revealed that all initiation complexes share a conserved core. This core consists of the RNA polymerase (I, II, or III), the TATA box-binding protein (TBP), and transcription factors TFIIB, TFIIE, and TFIIF (for Pol II) or proteins structurally and functionally related to parts of these factors (for Pol I and Pol III). The conserv...

RNA polymerase III (Pol III) transcribes small untranslated RNAs, such as tRNAs. To define the Pol III transcriptome in Saccharomyces cerevisiae, we performed genome-wide chromatin immunoprecipitation using subunits of Pol III, TFIIIB and TFIIIC. Virtually all of the predicted targets of Pol III, as well as several novel candidates, were occupied by Pol III machinery. Interestingly, TATA box-bi...

During gene transcription, the RNA polymerase (Pol) active center can catalyze RNA cleavage. This intrinsic cleavage activity is strong for Pol I and Pol III but very weak for Pol II. The reason for this difference is unclear because the active centers of the polymerases are virtually identical. Here we show that Pol II gains strong cleavage activity when the C-terminal zinc ribbon domain (C-ri...

This study describes a potential new function of hnRNP U as an RNA polymerase (Pol II) elongation inhibitor. We demonstrated that a subfraction of human hnRNP U is associated with the Pol II holoenzyme in vivo and as such recruited to the promoter as part of the preinitiation complex. hnRNP U, however, appears to dissociate from the Pol II complex at the early stage of transcription and is ther...

Genes coding for DNA polymerases eta, iota and zeta, or for both Pol eta and Pol iota have been inactivated by homologous recombination in the Burkitt's lymphoma BL2 cell line, thus providing for the first time the total suppression of these enzymes in a human context. The UV sensitivities and UV-induced mutagenesis on an irradiated shuttle vector have been analyzed for these deficient cell lin...