Difference between revisions of "Part:BBa K4061000"

Revision as of 13:29, 19 October 2021

OmpF promoter, controlled by OmpR regulatory protein as part of the Two Component System in E. coli

OmpF promoter is a OmpR regulated promoter that is activated under low medium osmolarity in E. coli especially. This promoter is reciprocally regulated with OmpC promoter (Bba_R0082) depending on the medium osmolarity. OmpF promoter is preferentially expressed in low medium osmolarity. In low osmolarity, the kinase activity of EnvZ (a histidine kinase) is repressed, leading to low concentration of phosphorylated OmpR (OmpR~P). Lower concentration of OmpR~P positively regulates the promoter by binding to high affinity sites (F1, F2, F3). At increased concentration of OmpR~P which occurs at a higher osmolarity, the OmpR~P binds the low affinity F4 site on the promoter which acts a negative regulator and represses the expression of OmpF promoter.

Usage and Biology

This promoter natively regulates the OmpF porin protein which has a relatively large diameter of pore. This is preferentially expressed on E. coli membrane in times when the environment osmolarity is extremely low and the nutrients are scarce. This way, the organism ensures appropriate exchange of ions and nutrients in order to maintain a good osmotic balance when internal osmolarity also starts to drop.

Sequence and Features