TY - JOUR
T1 - Blue light regulated two-component systems
T2 - Enzymatic and functional analyses of light-oxygen-voltage (LOV)-histidine kinases and downstream response regulators
AU - Correa, Fernando
AU - Ko, Wen Huang
AU - Ocasio, Victor
AU - Bogomolni, Roberto A.
AU - Gardner, Kevin H.
PY - 2013/7/9
Y1 - 2013/7/9
N2 - Light is an essential environmental cue for diverse organisms. Many prokaryotic blue light photoreceptors use light, oxygen, voltage (LOV) sensory domains to control the activities of diverse output domains, including histidine kinases (HK). Upon activation, these proteins autophosphorylate a histidine residue before subsequently transferring the phosphate to an aspartate residue in the receiver domain of a cognate response regulator (RR). Such phosphorylation activates the output domain of the RR, leading to changes in gene expression, protein-protein interactions, or enzymatic activities. Here, we focus on one such light sensing LOV-HK from the marine bacterium Erythrobacter litoralis HTCC2594 (EL368), seeking to understand how kinase activity and subsequent downstream effects are regulated by light. We found that photoactivation of EL368 led to a significant enhancement in the incorporation of phosphate within the HK domain. Further enzymatic studies showed that the LOV domain affected both the LOV-HK turnover rate (kcat) and K m in a light-dependent manner. Using in vitro phosphotransfer profiling, we identified two target RRs for EL368 and two additional LOV-HKs (EL346 and EL362) encoded within the host genome. The two RRs include a PhyR-type transcriptional regulator (EL-PhyR) and a receiver-only protein (EL-LovR), reminiscent of stress-triggered systems in other bacteria. Taken together, our data provide a biochemical foundation for this light-regulated signaling module of sensors, effectors, and regulators that control bacterial responses to environmental conditions.
AB - Light is an essential environmental cue for diverse organisms. Many prokaryotic blue light photoreceptors use light, oxygen, voltage (LOV) sensory domains to control the activities of diverse output domains, including histidine kinases (HK). Upon activation, these proteins autophosphorylate a histidine residue before subsequently transferring the phosphate to an aspartate residue in the receiver domain of a cognate response regulator (RR). Such phosphorylation activates the output domain of the RR, leading to changes in gene expression, protein-protein interactions, or enzymatic activities. Here, we focus on one such light sensing LOV-HK from the marine bacterium Erythrobacter litoralis HTCC2594 (EL368), seeking to understand how kinase activity and subsequent downstream effects are regulated by light. We found that photoactivation of EL368 led to a significant enhancement in the incorporation of phosphate within the HK domain. Further enzymatic studies showed that the LOV domain affected both the LOV-HK turnover rate (kcat) and K m in a light-dependent manner. Using in vitro phosphotransfer profiling, we identified two target RRs for EL368 and two additional LOV-HKs (EL346 and EL362) encoded within the host genome. The two RRs include a PhyR-type transcriptional regulator (EL-PhyR) and a receiver-only protein (EL-LovR), reminiscent of stress-triggered systems in other bacteria. Taken together, our data provide a biochemical foundation for this light-regulated signaling module of sensors, effectors, and regulators that control bacterial responses to environmental conditions.
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U2 - 10.1021/bi400617y
DO - 10.1021/bi400617y
M3 - Article
C2 - 23806044
AN - SCOPUS:84880081182
SN - 0006-2960
VL - 52
SP - 4656
EP - 4666
JO - Biochemistry
JF - Biochemistry
IS - 27
ER -