Abstract In eukaryotes, three RNA polymerases (RNAPs) play essential roles in the synthesis of various types of RNA: namely, RNAPI for rRNA; RNAPII for mRNA and most snRNAs; and RNAPIII for tRNA and Show more
Abstract In eukaryotes, three RNA polymerases (RNAPs) play essential roles in the synthesis of various types of RNA: namely, RNAPI for rRNA; RNAPII for mRNA and most snRNAs; and RNAPIII for tRNA and other small RNAs. All three RNAPs possess a short flexible tail derived from their common subunit RPB6. However, the function of this shared N-terminal tail (NTT) is not clear. Here we show that NTT interacts with the PH domain (PH-D) of the p62 subunit of the general transcription/repair factor TFIIH, and present the structures of RPB6 unbound and bound to PH-D by nuclear magnetic resonance (NMR). Using available cryo-EM structures, we modelled the activated elongation complex of RNAPII bound to TFIIH. We also provide evidence that the recruitment of TFIIH to transcription sites through the p62âRPB6 interaction is a common mechanism for transcription-coupled nucleotide excision repair (TC-NER) of RNAPI- and RNAPII-transcribed genes. Moreover, point mutations in the RPB6 NTT cause a significant reduction in transcription of RNAPI-, RNAPII-Â and RNAPIII-transcribed genes. These and other results show that the p62âRPB6 interaction plays multiple roles in transcription, TC-NER, and cell proliferation, suggesting that TFIIH is engaged in all RNAP systems. Show less
Abstract TFIIH is a 10âsubunit complex that regulates RNA polymerase II (pol II) transcription but also serves other important biological roles. Although much remains unknown about TFIIH function in Show more
Abstract TFIIH is a 10âsubunit complex that regulates RNA polymerase II (pol II) transcription but also serves other important biological roles. Although much remains unknown about TFIIH function in eukaryotic cells, much progress has been made even in just the past few years, due in part to technological advances (e.g. cryoEM and single molecule methods) and the development of chemical inhibitors of TFIIH enzymes. This review focuses on the major cellular roles for TFIIH, with an emphasis on TFIIH function as a regulator of pol II transcription. We describe the structure of TFIIH and its roles in pol II initiation, promoterâproximal pausing, elongation, and termination. We also discuss cellular roles for TFIIH beyond transcription (e.g. DNA repair, cell cycle regulation) and summarize small molecule inhibitors of TFIIH and diseases associated with defects in TFIIH structure and function. Show less
Significance RNAP1 transcription, dedicated to ribosomal DNAs (rDNAs), is the first and rate-limiting step of ribosome biogenesis. rDNAs are grouped into several copies. This redundancy is important t Show more
Significance RNAP1 transcription, dedicated to ribosomal DNAs (rDNAs), is the first and rate-limiting step of ribosome biogenesis. rDNAs are grouped into several copies. This redundancy is important to guarantee that at low damage levels one rDNA gene can be temporarily silenced without affecting overall ribosome biogenesis. Nevertheless, when DNA repair is defective or overloaded, several rDNAs could be damaged, disturbing the whole RNAP1 transcription process and later on modifying the ribosome content of cells. Therefore, it is of fundamental importance for the cell to maintain a functional RNAP1 transcription by repairing DNA lesions on rDNAs. In this work we identified, in mammals, the repair mechanism of rDNAs along with a specific behavior for RNAP1 after UV irradiation. Show less
Chromatin DNA must be read out for various cellular functions and copied for the next cell division. These processes are targets of many anticancer agents. Platinum-based drugs, such as cisplatin, hav Show more
Chromatin DNA must be read out for various cellular functions and copied for the next cell division. These processes are targets of many anticancer agents. Platinum-based drugs, such as cisplatin, have been used extensively in cancer chemotherapy. The drugâDNA interaction causes DNA crosslinks and subsequent cytotoxicity. Recently, it was reported that an azolato-bridged dinuclear platinum(II) complex, 5-H-Y, exhibits a different anticancer spectrum from cisplatin. Here, using an interdisciplinary approach, we reveal that the cytotoxic mechanism of 5-H-Y is distinct from that of cisplatin. 5-H-Y inhibits DNA replication and also RNA transcription, arresting cells in the S/G2 phase and are effective against cisplatin-resistant cancer cells. Moreover, it causes much less DNA crosslinking than cisplatin and induces chromatin folding. 5-H-Y will expand the clinical applications for the treatment of chemotherapy-insensitive cancers. Show less