Figure 10.

Role of key residues in peptide-induced acceleration of CheY phoshorylation. (a) Active site features of CheY in BeF₃⁻-free ^F432YZ_200-214 superimposed on inactive Mg²⁺-bound CheY. (b) Active site features of CheY in BeF₃⁻-bound ^P2(1)2(1)2YZ_200-214 superimposed on BeF₃⁻-activated CheY. Key features in BeF₃⁻-free ^F432YZ_200-214 are shown in cyan, in BeF₃⁻-bound ^P2(1)2(1)2YZ_200-214 in orange, in inactive Mg²⁺-bound CheY in red and in BeF₃⁻-activated CheY in green. The Mg²⁺ ion (magenta), water molecules (deep red) and the BeF₃⁻species (yellow) at the active site are shown. The BeF₃⁻-free ^F432YZ_200-214 structure solved from a crystal grown in Tris (pH 8.4) is used as a representative of all ^F432YZ_200-214 structures in (a). (c) Role of ¹⁴Phe and ⁵⁹Asn. Rates of phosphotransfer to WT CheY, CheY¹⁴F→A and CheY⁵⁹N→A proteins from ammonium phosphoramidate in the presence (+) and absence (−) of the CheZ_200-214 peptide are shown as bars (see Materials and Methods). Each rate corresponds to an average from three independent experiments with standard errors indicated.