Nutrient Transport - Advanced Exercise 2
EnvZ and OmpR proteins play a key role in regulating the transcription of genes encoding outer membrane porins in E. coli.
- What type of regulation system do these proteins form, and which type of protein in that system is EnvZ?
- What stretch of residues is necessary for ATP binding in EnvZ?
- What is the mechanism of autophosophorylation of EnvZ considering that it forms a dimer, and which amino acid is phosphorylated? (Hint: Find the reaction page for the autophosphorylation.)
- EnvZ phosphorylates OmpR. What resets this regulatory system, i.e. what converts OmpR back to its unphosphorylated state? (Hint: refer to the associated Reaction page.)
- Under “Sequence Features” for EnvZ, what amino acid at position 347 was mutated? What was it mutated to? How would porin expression be impacted by this mutation?
- What mutations in OmpR would give a similar phenotype to that described in your answer to e? Give your answer in terms of general domains rather than specific amino acids.