Structure of RNA polymerase

Figure 37-9. The eukaryotic basal transcription complex. Formation of the basal transcription complex begins when TFIID binds to the TATA box. It directs the assembly of several other components by protein-DNA and protein-protein interactions. The entire complex spans DNA from position -30 to +30 relative to the initiation site (+1, marked by bent arrow). The atomic level, x-ray-derived structures of RNA polymerase II alone and ofTBP bound to TATA promoter DNA in the presence of either TFIIB or TFIIA have all been solved at 3 A resolution. The structure of TFIID complexes have been determined by electron microscopy at 30 A resolution. Thus, the molecular structures of the transcription machinery are beginning to be elucidated. Much of this structural information is consistent with the models presented here.

The structure of RNA polymerase, the signals that control transcription, and the varieties of modification that RNA transcripts can undergo dffer among organisms, and particularly from prokaryotes to eukaryotes. Therefore, in this chapter, the discussions of prokaryotic and eukaryotic transcription are presented separately. 

Figure 28-4 (A) Hypothetical structure of a "transcription bubble" formed by an RNA polymerase. Shown is a double-stranded length of DNA with the unwound bubble in the center. This contains a short DNA-RNA hybrid helix formed by the growing mRNA. The DNA double helix is undergoing separation at point A as is the hybrid helix at point B. NTP is the ribonucleotide triphosphate substrate. See Yager and von Hippel.71 (B) Stereoscopic view of the structure of RNA polymerase from Thermus aquaticus in a complex with a promoter DNA. Included are the al, all, (0, (3, P, and a subunits. However, the a C-terminal domains have been omitted. The template (t) strand passes through a tunnel, which is formed by the P and P subunits and two of the structural domains of the a subunit. The nontemplate (nt) strand follows a different path. The position of the -10, -35, and UP elements of the DNA are marked. From Murakami et al.33d Courtesy of Seth A. Darst.

Figure 28.1. RNA Polymerase Structures. The three-dimensional structures of RNA polymerases from a prokaryote...

Structure of RNA Polymerases The RNA polymerases of bacteria, archaea, and eukaryotic cells are fundamentally similar In structure and function. Bacterial RNA polymerases are composed of two related large subunits (P and P), two copies of a smaller subunit (ct), and one copy of a fifth subunit (m) that is not essential for transcription or cell viability but stabilizes the enzyme and assists In the assembly of Its subunits. Archaeal and eukaryotic RNA polymerases have several additional small subunits associated with this core complex, which we describe in Chapter 11. Schematic dia-... 

See also Structure of RNA Polymerase, Interactions with Promoters, Initiation and Elongation, Factor-Independent Termination of Transcription, Factor-Dependent Termination of Transcription... 

See also Initiation and Elongation, Structure of RNA Polymerase, Transcription Regulation in Phage, Lactose Operon Regulation, Supercoiling (from Chapter 4)... 

The chapter begins -with an overview of the three stages of RNA synthesis initiation, elongation, and termination. The subunit structure of RNA polymerase from... 

Describe the subunit structure of RNA polymerase from E. coli, and assign functions to the individual subunits. 

Polypeptide Structure of RNA Polymerase II from Various Eukaryotic... 

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