FIG 5 .

Switching specificity determinants alters binding, phosphotransfer, and phosphatase affinity. (A) Domain topology of the prototypical histidine kinase CrdS with a DHp α1 helix sequence alignment for CrdS, HK1190, and the chimeric CrdS6. (B) Phosphotransfer profiling demonstrates that the chimeric CrdS6 protein mimics the phosphotransfer specificity of HK1190. Three separate gels were run and processed simultaneously to enable profiling for all 25 RRs. The resulting images were assembled into one row as shown. Phosphatase assays demonstrate that specificity for CrdS6 has been switched from CrdA~P (C) to NtrC1189~P (D).