7 Transcription Factors and Transcriptional Regulation

Abstract

I. INTRODUCTION
Particular aspects of Caenorhabditis elegans biology — embryonic development, sex determination, muscle and nerve biology, and so on — are considered in other chapters in this volume. This chapter focuses on a theme common to many of these chapters, namely, transcription factors and the regulation of genes transcribed by RNA polymerase II.

A recent compendium of human gene sequences (Adams et al. 1995) suggests that 7–8% of all genes code for transcription factors. If the same gene distribution applies to the approximately 13,000 genes in the C. elegans genome, then C. elegans must have 1000 such factors. C. elegans sequence databases contain many examples of classes of proteins that are known to control transcription in other organisms, and the genome sequencing project will soon provide a complete inventory. The task will then be to identify the genes that all of these factors regulate.

The first section of the present chapter summarizes information on the basal transcription machinery in C. elegans. The second section describes the most important properties of known transcription factors in C. elegans. The final section summarizes studies that have begun to unravel the transcriptional control of particular genes by analyzing their promoters.

II. THE BASAL TRANSCRIPTION MACHINERY
Although several features of C. elegans transcription are unusual (e.g., trans-splicing and the arrangement of genes in operons), the basic transcriptional machinery is likely to be highly similar, both structurally and functionally, to that found in other eukaryotes. For example, RNA polymerase II from C. elegans behaves much like...