NE224 Lecture Notes - Lecture 15: Arabinose, Operon, Repressor

• School: University of Waterloo
• Department: Nanotechnology Engineering
• Course: NE224
• Professor: Elizabeth Meiering

Document Summary

Transcription control: lac (lactose) operon, arabad (arabinose) operon. This is more thoroughly characterized for prokaryotic cells than eukaryotic cells. Proteins bound to the dna are an important way that transcription is controlled. A common dna recognition element is a helix-turn-helix. -helix dimensions similar to major groove (~1. 2 nm width) e. g. dimeric 434 phage repressor bound to dna. 2-turn- 3 binds to major groove e. g. dimeric trp repressor:tgtactagttaactagtac:trp corepressor. But -strands can also be used for specific dna binding e. g. dimeric met repressor:dna:s-adenosylmethionine (sam) corepressor. Reg"n of transcription p4 of 9 laci = lac repressor. Binds to operator and represses transcription of the operon lacz = -galactosidase. Hydrolyzes -glycosidic linkage of disaccharide lactose to form the monosaccharides galactose and glucose lacy = lactose (galactoside) permease. Membrane bound transport protein that pumps lactose into the cell laca = -galactoside transacetylase. What proteins are involved in the control of the lac operon? (i) lac repressor: see above.