MBIO 4612 Lecture Notes - Lecture 18: Helicase, Deoxyribonuclease I, Nucleosome

• School: University of Manitoba
• Department: Microbiology
• Course: MBIO 4612
• Professor: Peter Pelka

Document Summary

Name origin from genes identified in 2 different experiments: mating type switching genes switch genes = swi, sucrose metabolism genes sucrose nonfermenting = snf. Sequence comparison showed that swi2 + snf2 were the same gene. Function = transcriptional activation or repression (often counteracts transcriptional silencing of chromatin) Found that suppressors of defective swi/snf complexes were chromatin components: histone mutants restore the activator response in swi/snf deficient strains. Increases accessibility of nucleosomal dna to dnase i & other nucleases. All known chromatin remodeling complexes bind chromatin directly & use atp for energy: facilitates tf binding (activators or repressors) to nucleosome by changing chromatin structure. This is an active energy dependent process! Swi2 = motor of the machine: has dna-stimulated atpase activity, mutating the atpase causes non- functional swi/snf complexes, resembles a dna helicase. Atp-hydrolysis increases accessibility of nucleosomal dna to transacting factors. This shows that in order for chromatin remodeling to occur, the remodeling factor needs atp to function!