The gammaherpesviral TATA-box-binding protein directly interacts with the CTD of host RNA Pol II to direct late gene transcription

Abstract

β-and γ-herpesviruses include the oncogenic human viruses Kaposi's sarcoma-associated virus (KSHV) and Epstein-Barr virus (EBV), and human cytomegalovirus (HCMV), which is a significant cause of congenital disease. Near the end of their replication cycle, these viruses transcribe their late genes in a manner distinct from host transcription. Late gene transcription requires six virally encoded proteins, one of which is a functional mimic of host TATA-box-binding protein (TBP) that is also involved in recruitment of RNA polymerase II (Pol II) via unknown mechanisms. Here, we applied biochemical protein interaction studies together with electron microscopy-based imaging of a reconstituted human preinitiation complex to define the mechanism underlying Pol II recruitment. These data revealed that the herpesviral TBP, encoded by ORF24 in KSHV, makes a direct protein-protein contact with the C-terminal domain of host RNA polymerase II (Pol II), which is a unique feature that functionally distinguishes viral from cellular TBP. The interaction is mediated by the N-terminal domain (NTD) of ORF24 through a conserved motif that is shared in its β-and γ-herpesvirus homologs. Thus, these herpesviruses employ an unprecedented strategy in eukaryotic transcription, wherein promoter recognition and polymerase recruitment are facilitated by a single transcriptional activator with functionally distinct domains.

Differences in RNA polymerase II complexes and their interactions with surrounding chromatin on human and cytomegalovirus genomes

“…We therefore propose that while TFIIH is required for UL87 initiation, it is not a stable component of the UL87 PIC that we detect. A recent study regarding ORF24, a UL87 homolog in Kaposi’s sarcoma associated virus 20 , showed association with the Pol II CTD only in the hypophosphorylated state, which is in agreement with our data demonstrating that the Pol II in UL87 PIC is predominantly unphosphorylated 48 . Regardless of these functional differences, both PICs function on a large shared subset of HCMV promoters.…”

Differences in RNA polymerase II complexes and their interactions with surrounding chromatin on human and cytomegalovirus genomes

“…We therefore propose that while TFIIH is required for UL87 initiation, it is not a stable component of the UL87 PIC that we detect. A recent study regarding ORF24, a UL87 homolog in Kaposi's sarcoma associated virus 20 , showed association with the Pol II CTD only in the hypophosphorylated state, which is in agreement with our data demonstrating that the Pol II in UL87 PIC is predominantly unphosphorylated 45 . Regardless of these functional differences, both PICs function on a large shared subset of HCMV promoters.…”

Vaccinia virus D10 has broad decapping activity that is regulated by mRNA splicing

“…Like DCP2, VACV D10 contains a Nudix hydrolase domain [ 19 ]; however, it lacks the inhibitory C-terminal domain, supporting the hypothesis that D10 may function as a constitutively active decapping enzyme. Indeed, many viruses encode proteins that functionally mimic cellular factors but have evolved to have reduced or novel regulation [ 2 – 4 , 20 , 21 ]. Here, we tested this hypothesis by defining the breadth of VACV D10 targets by RNA sequencing.…”