Multiple signals modulate the activity of the complex sensor kinase T od S

Summary The reason for the existence of complex sensor kinases is little understood but thought to lie in the capacity to respond to multiple signals. The complex, seven‐domain sensor kinase T od S controls in concert with the T od T response regulator the expression of the toluene dioxygenase pathway in P seudomonas putida   F 1 and DOT ‐ T 1 E . We have previously shown that some aromatic hydrocarbons stimulate T od S activity whereas others behave as antagonists. We show here that T od S responds in addition to the oxidative agent menadione. Menadione but no other oxidative agent tested inhibited T od S activity in vitro and reduced P todX expression in vivo . The menadione signal is incorporated by a cysteine‐dependent mechanism. The mutation of the sole conserved cysteine of T od S ( C 320) rendered the protein insensitive to menadione. We evaluated the mutual opposing effects of toluene and menadione on T od S autophosphorylation. In the presence of toluene, menadione reduced T od S activity whereas toluene did not stimulate activity in the presence of menadione. It was shown by others that menadione increases expression of glucose metabolism genes. The opposing effects of menadione on glucose and toluene metabolism may be partially responsible for the interwoven regulation of both catabolic pathways. This work provides mechanistic detail on how complex sensor kinases integrate different types of signal molecules.