Rpb5, a subunit shared by eukaryotic RNA polymerases, cooperates with prefoldin-like Bud27/URI

Abstract

Rpb5 is one of the five common subunits to all eukaryotic RNA polymerases, which is conserved in archaea, but not in bacteria. Among these common subunits, it is the only one that is not interchangeable between yeasts and humans, and accounts for the functional incompatibility of yeast and human subunits. Rpb5 has been proposed to contribute to the gene-specific activation of RNA pol II, notably during the infectious cycle of the hepatitis B virus, and also to participate in general transcription mediated by all eukaryotic RNA pol. The structural analysis of Rpb5 and its interaction with different transcription factors, regulators and DNA, accounts for Rpb5 being necessary to maintain the correct conformation of the shelf module of RNA pol II, which favors the proper organization of the transcription bubble and the clamp closure of the enzyme.In this work we provide details about subunit Rpb5's structure, conservation and the role it plays in transcription regulation by analyzing the different interactions with several factors, as well as its participation in the assembly of the three RNA pols, in cooperation with prefoldin-like Bud27/URI.

A remodeled RNA polymerase II complex catalyzing viroid RNA-templated transcription

“…Interestingly, Rpb4/Rpb7 heterodimer is present in all archaeal and eukaryotic cells but not in bacteria [ 10 , 52 ], further suggesting that organization changes occurred in RNA polymerases during the course of evolution. The remodeled Pol II identified here only retains a minimal set of factors, while most of the missing subunits are absent in bacterial RNA polymerases (i.e., Rpb4, Rpb5, Rpb7, and Rpb9) [ 53 – 55 ]. Our discovery of a remodeled Pol II actively transcribing RNA templates may provide a handle to further explore the functional evolution of transcription machinery.…”

Prefoldin Subunits and Its Associate Partners: Conservations and Specificities in Plants

“…For example, the RPB5-binding domain in this region is essential for RNA polymerase-related events. Both the human URI and its yeast ortholog Bud27 bind and regulate the stability of RPB5, a common subunit of three eukaryotic RNA polymerases, affecting RNA polymerase assembly or activity [ 19 , 21 , 22 , 112 ]. Yeast Bud27 also regulates RNA polymerase-dependent transcription and ribosome biogenesis processes [ 113 , 114 ].…”

The functions and mechanisms of prefoldin complex and prefoldin-subunits

“…URI is the alpha subunit of PFDL and is also called RNA polymerase II fifth subunit regulatory protein (RMP) [85]. In the cytoplasm, URI acts as a chaperone protein; in the nucleus, URI acts as a transcription regulator and can interact with RPB5 (a subunit common to three eukaryotic RNA polymerases) and RNA polymerase II (pol II) [86,87]. URI has strong oncogenic activity because it can regulate the functions of many proteins including transcription factors (ERα and AhR) [86].…”

“…In the cytoplasm, URI acts as a chaperone protein; in the nucleus, URI acts as a transcription regulator and can interact with RPB5 (a subunit common to three eukaryotic RNA polymerases) and RNA polymerase II (pol II) [86,87]. URI has strong oncogenic activity because it can regulate the functions of many proteins including transcription factors (ERα and AhR) [86]. For example, in a mouse model, excessive expression of URI in hepatocytes can lead to hepatocellular carcinoma (HCC) [85]; decreasing the expression of URI in the intestine will activate the c-Myc expression induced by β-catenin, leading to mouse cell proliferation, DNA damage, and susceptibility to fatal gastrointestinal syndrome (GIS) caused by ionizing radiation (IR) [88].…”