Nuclear multisubunit RNA polymerases IV and V (Pol IV and Pol V) evolved in plants as specialized forms of Pol II. Their functions are best understood in the context of RNA-directed DNA methylation (RdDM), a process in which Pol IV-dependent 24 nt siRNAs direct the de novo cytosine methylation of regions transcribed by Pol V. Pol V has additional functions, independent of Pol IV and 24 nt siRNA...

The dnaN159 allele encodes a temperature-sensitive mutant form of the β sliding clamp (β159). SOS-induced levels of DNA polymerase IV (Pol IV) confer UV sensitivity upon the dnaN159 strain, while levels of Pol IV ∼4-fold higher than those induced by the SOS response severely impede its growth. Here, we used mutations in Pol IV that disrupted specific interactions with the β clamp to test our hy...

DNA replication in eukaryotes is asymmetric, with separate DNA polymerases (Pol) dedicated to bulk synthesis of the leading and lagging strands. Pol α/primase initiates primers on both strands that are extended by Pol e on the leading strand and by Pol δ on the lagging strand. The CMG (Cdc45-MCM-GINS) helicase surrounds the leading strand and is proposed to recruit Pol e for leading-strand synt...

The bypass of DNA lesions by the replication fork requires a switch between the replicative DNA polymerase (Pol) and a more specialized translesion synthesis (TLS) Pol to overcome the obstacle. DNA Pol δ-interacting protein 2 (PolDIP2) has been found to physically interact with Pol η, Pol ζ, and Rev1, suggesting a possible role of PolDIP2 in the TLS reaction. However, the consequences of PolDIP...

To further our understanding of the structural and functional organization of the Trypanosoma brucei genome, we have searched for and analyzed sites in the genome where Pol II transcription units meet Pol III genes. Physical and transcriptional maps of cosmid clones spanning the Pol III-transcribed U2 small nuclear RNA (snRNA) and U3 snRNA/7SL RNA gene loci demonstrated that single-copy Pol II ...

The gene encoding yeast U6 snRNA that is transcribed by RNA polymerase III (Pol III) contains both a TATA box upstream of the transcription start site and a downstream binding site for the factor TFIIIC. This juxtaposition of elements typical of both Pol II- and Pol III-transcribed genes raises the question of how polymerase specificity is determined. The upstream U6 promoter containing the TAT...

It has been reported recently that the human foamy virus (HFV) Pol polyprotein of 120 kDa is synthesized in the absence of the active HFV aspartic protease. To gain more information on how the 120-kDa Pro-Pol protein is synthesized, mutant HFV genomes were constructed and the resulting proviruses were analyzed with respect to HFV pol expression and infectivity. HFV proviruses that contain termi...

Mutants of Saccharomyces cerevisiae have been selected for resistance to the polyene antibiotics, etruscomycin, filipin, nystatin, pimaricin and rimocidin. All mutants are resistant to nystatin and there are several patterns of cross-resistance. The mutants were allocated to four unlinked genes pol I , 2, 3 and 5. A fifth gene, pol 4, was recovered as a double mutant with a strain carrying the ...

The task of transcribing nuclear genes is shared between three RNA polymerases in eukaryotes: RNA polymerase (pol) I synthesizes the large rRNA, pol II synthesizes mRNA and pol III synthesizes tRNA and 5S rRNA. Although pol II has received most attention, pol I and pol III are together responsible for the bulk of transcriptional activity. This survey will summarise what is known about the proce...