MICB 325 Lecture Notes - Lecture 5: Histidine Kinase, T-Cell Receptor, Signal Transduction
Document Summary
Bacteria respond to changing environments by altering gene expression. In its most basic form, a tcrs consists of a membrane-bound sensor kinase and a. In response to specific stimuli, the sensor kinase is phosphorylated at a conserved histidine residue and then the phosphoryl group is transferred to the conserved aspartate on the response regulator. Phosphorylation of the response regulator triggers a conformational change, driving dimerization and high affinity dna binding. For example, envz is a sensor kinase that spans the inner cytoplasmic membrane and has two domains- a sensory domain and a transmitter domain. In response to osmotic changes, envz is phosphorylated at a conserved histidine residue and then the phosphoryl group is transferred to the conserved aspartate on the response regulator, ompr (see figure 1). Phosphorylation of ompr triggers a conformational change, driving dimerization and high affinity dna binding. Bacteria differ from eukaryotes in that their signal transduction systems employ histidine phosphorylation rather than tyrosine phosphorylation [1].
