Figure 9.

Models of complexes for the phosphotransferase and kinase reactions catalyzed by HK853-CD. (A) Ribbon representation of the experimental complex (Zapf et al, 2000) between Spo0B (green and yellow) and Spo0F (red). For clarity, only one Spo0F molecule is drawn. (B) The Spo0F RR (red) docked onto the HK853–CD dimer (green and yellow) as a model of the phosphotransferase complex (see text). The catalytic histidine and aspartate residues and the nucleotide are shown as stick models. (C) Orthogonal view of (B). (D) Model of HK853–CD poised for the autokinase reaction. The catalytic domain of one protomer has been moved to align the γ phosphate of its ATP moiety with the phosphoaccepting histidine of the other promoter to permint trans-phosphorylation. The histidine and nucleotide are shown in stick representation. (E) Orthogonal view of (D).