Protein–Protein Contacts that Activate and Repress Prokaryotic Transcription

• Published in: Cell Vol. 92; no. 5; pp. 597 - 600
• Main Authors: Hochschild, Ann, Dove, Simon L
• Format: Book Review Journal Article
• Language: English
• Published: United States Elsevier Inc 06-03-1998
• Subjects: Bacteria - genetics; DNA - metabolism; DNA-Directed RNA Polymerases - metabolism; Repressor Proteins - metabolism; Trans-Activators - metabolism; Transcription, Genetic - physiology
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/S0092-8674(00)81126-5

Many prokaryotic activators and repressors contact RNA polymerase (RNAP) directly, and this minreview focuses on recent work that illuminates the mechanistic consequences of these protein-protein contacts. An important implication of this work is that the promoter is a critical determinant that dictates whether a given protein-protein contact will have an effect on transcription, what the effect will be (activation or repression), and which specific step(s) in the initiation process will be targeted. In vitro studies have led to the following general picture of transcription initiation. RNAP first recognizes and binds to double-stranded promoter DNA, forming a complex that is referred to as the "closed" complex. This must then isomerize to form a transcriptionally active open complex in which the DNA strands are locally melted. At this stage RNAP can direct the synthesis of short abortive products, but for full-length transcripts to be generated, RNAP must also escape from the promoter; this involves breaking contacts that stabilize the open complex. Thus, activators and repressors can, in theory, affect closed complex formation, open complex formation, or promoter clearance.