from David A. Jacques, J. Mitchell Guss and Jill Trewhella writing in Two-Component Systems in Bacteria:
Antikinases are protein inhibitors of the bacterial sensor histidine kinases found in two-component systems. Antikinases act by binding the highly-conserved autokinase domains and thereby inhibit autophosphorylation. Antikinases offer unique opportunities to understand histidine kinase function and inhibition, and as histidine kinases are not found in mammals, knowledge of their structures and binding can potentially be exploited for the development of novel antimicrobial compounds. This review describes our current understanding of the three known antikinases: Sda and KipI from Bacillus subtilis and FixT from Sinorhizobium meliloti, with a focus on understanding of their detailed structures and mechanisms of action.
Further reading: Two-Component Systems in Bacteria