UirS is a transmembrane dual-cysteine UV/Green cyanobacteriochrome protein which tethers UirR at the membrane when in the ground state. The TC UirS is encoded as 1 of 16 two-component signalling gene clusters in Synechocystis (Ashby MK, Houmard J, 2006). Activation of UirS results in a signal transduction cascade - UirS phosphorylates UirR, causing the protein to dissociate from UirS and dimerise. In dimeric form, UirR-P acts as a specific transcriptional activator at the lsiR operator.
This CDS is part of a two-component system (TCS) originally derived from the unicellular cyanobacterium Synechocystis sp. PCC6803. Like most TCS, the system comprises a transmembrane histidine kinase sensor - UirS (K1725410); a cytoplasmic response regulator - UirR (K1725420); and an output promoter - LsiR (this part, K1725400).
The promoter is normally off and activated in response to UV-A by the release of UirR (K1725420) from the transmembrane protein UirS (K1725410) and binding at the operator region within the promoter LsiR. UirS activation is photoreversible, flipped from the ground state into an activated state when irradiated by UV-A (in the range of 382nm-405nm) and inactivated when exposed to green light (lambda = 534nm).
Prabha Ramakrishnan and Jeffrey J. Tabor (2016) showed that in the absence of green light, sfGFP (downstream of PcsiR) followed an activating Hill-like response with increasing UV-violet intensity up to 12umol m^-2 s^-1 while varying intensities of green light decreased the binding sensitivity of UirR and UirS.
For the promoter to be activated all three parts must be present and the cell has to be exposed to UV-A. .
Sequence and Features
- 10COMPATIBLE WITH RFC
- 12COMPATIBLE WITH RFC
- 21Illegal BglII site found at 567
Illegal BglII site found at 1422
Illegal XhoI site found at 1790
- 23COMPATIBLE WITH RFC
- 25COMPATIBLE WITH RFC
- 1000COMPATIBLE WITH RFC