Basic Studies in Transcription Toward a New Era of Molecular Biology

**151**

**1. Introduction**

**Chapter 8**

*pombe*

**Abstract**

*and Edio Maldonado*

Transcriptional Initiation in

Ribosomal Protein Genes in the

*Diego A. Rojas, Sandra Moreira-Ramos, Fabiola Urbina* 

Transcription of class II genes in eukaryotic organisms is carried out by the multi-

subunit enzyme RNA polymerase II (RNA pol II) and includes the general transcription factors and the mediator. The region inside the promoters, which recruits and specifies the transcriptional machinery, is called "core promoter" and contains sub-regions called "core promoter elements," which are necessary for transcription initiation, where the most studied and classic element is the TATA-box. Ribosome protein gene (RPG) promoters do not possess a TATA-box (TATA-less promoters), and those, in particular, in the fission yeast *Schizosaccharomyces pombe* have a TATAbox analog called the HomolD-box. The transcription of RPG promoters is dependent on the RNA pol II transcription system and the HomolD-box is recognized by the transcription factor Rrn7. In this chapter, the authors will describe the general mechanisms associated to the transcription of TATA-less promoters in eukaryotic organisms and how the transcription initiation is carried out in the RPG promoters from those organisms, particularly in *Schizosaccharomyces pombe*. Finally, the authors will analyze the role of the HomolD-box and the transcription factor Rrn7 in the coordination of transcription initiation from RPG promoters and other ribosomerelated genes and the presence of transcriptional modules in their promoters, which could be coordinated and regulated by a discrete number of transcription factors.

**Keywords:** transcription, ribosomal protein gene (RPG), RNA polymerase,

Protein synthesis in eukaryotic organisms includes several steps and requires many regulatory events [1, 2]. One of these critical steps is ribosome biogenesis, which includes ribosomal protein gene (RPG) transcription and rRNA synthesis. As in many other central events in the cell, ribosome biosynthesis must be a regulated and coordinated process. A typical coordinated regulation of gene and protein expression is the presence of common DNA elements in the promoters of related genes, which are co-regulated by a discrete number of transcription factors. Those genes under the control of a common DNA element form a transcriptional

TATA-less promoter, *Schizosaccharomyces pombe*

Fission Yeast *Schizosaccharomyces* 
