Biochemistry 2280A Chapter : Topic 23.docx

• School: Western University
• Department: Biochemistry
• Course: Biochemistry 2280A
• Professor: Christopher Brandl

Document Summary

The dna sequence required for transcriptional initiation of a gene is called a promoter; promoters include sequences that recognize rna polymerase and recognize any gene specific regulatory factors. The dna sequence required for transcriptional termination is called the terminator. Transcription is catalyzed by the enzyme rna polymerase. Gene specific regulatory proteins (transcription factors) are the key molecules in the differential transcription of genes. Bacterial transcription is very similar to eukaryotic transcription in the basic process; but is somewhat simpler. We will first focus on bacterial transcription. The core enzyme will synthesize rna from ends or nicks in dna templates but it lacks promoter specificity (cannot recognize promoter sequences) Rna polymerase holoenzyme will transcribe rna specifically from promoters. Rna polymerase contains a sigma subunit which enhances recognition of promoter structures and decreases binding to nonpromoter dna. Rna polymerase recognizes and binds to the promoter dna; called closed complex.