The molecular puzzle of two-component signaling cascades

Two-component systems constitute prevalent signaling pathways in bacteria a nd mediate a large variety of adaptative cellular responses. Signaling proc eeds through His-Asp phosphorelay cascades that involve two central partner s, the histidine protein kinase and the response regulator protein. Structu ral studies have provided insights into some design principles and activati on mechanisms of these multi-domain proteins implicated in the control of v irulence gene expression in several pathogens. (C) 2001 Editions scientifiq ues et medicales Elsevier SAS.