Systematic Mapping of the Sequence Space Critical to Bacterial Signal Transduction

Cells have a remarkable ability to sense and respond to changes in their environment. This sensory capability often relies on membrane-embedded protein kinases that can relay information about the environment to intracellular effectors. In bacteria, such information transfer frequently involves two-component signal transduction pathways that transfer the signals from the outside to the interior of the cell. The signal transfer activates a specific transcription factor, which, in turn, will activate a set of genes that are necessary to respond to the specific environmental changes. In his previous work, the investigator studied the signal transfer system on the protein level and discovered four amino acid residues that are necessary for the two-component signal transduction partners to interact and subsequently activate the appropriate set of target genes. This is remarkable because bacterial cells have many such highly homologous parallel signal transduction systems that are dedicated to activate a highly diverse set of gene systems. This raises the question of how these pathways maintain their specificity with apparent minimal cross talk between them. The focus of this study is to assess how these four specificity residues ensure that the signal-receiving component of the system finds the cognate response regulator.