Volume 23, Issue 12, Pages 2331-2340 (December 2015) Protein Kinase A Catalytic Subunit Primed for Action: Time-Lapse Crystallography of Michaelis Complex Formation  Amit Das, Oksana Gerlits, Jerry M. Parks, Paul Langan, Andrey Kovalevsky, William T. Heller  Structure  Volume 23, Issue 12, Pages 2331-2340 (December 2015) DOI: 10.1016/j.str.2015.10.005 Copyright © 2015 Elsevier Ltd Terms and Conditions

Structure 2015 23, 2331-2340DOI: (10.1016/j.str.2015.10.005) Copyright © 2015 Elsevier Ltd Terms and Conditions

Figure 1 Simulated Annealing Omit Maps of the Active-Site Residues, Mg2+ Ions, and Coordinating Waters Omit maps are shown in blue at 3σ; coordinating waters are shown in red at 3σ. (A) Structure of T1. (B) Structure of T2. (C) Structure of T3. The curved double-headed arrow indicates the 111.4° rotation between the substrate S21A and S21B rotamers. See also Figure S1. Structure 2015 23, 2331-2340DOI: (10.1016/j.str.2015.10.005) Copyright © 2015 Elsevier Ltd Terms and Conditions

Figure 2 Hydrogen Bonding Hydrogen bonding in the active site of (A) T1, (B) T2, and (C) T3 structures. At T1, Mg2 has 0.5 occupancy. Mg2+ ions are shown as green spheres. See also Figure S2. Structure 2015 23, 2331-2340DOI: (10.1016/j.str.2015.10.005) Copyright © 2015 Elsevier Ltd Terms and Conditions

Figure 3 Active Site and Catalytic Cleft (A) Overlay of the active sites of the T1 (magenta), T2 (cyan), and T3 (yellow) PKAc structures. The ATP of the T1 structure is presented in gray. (B) Cartoon representation of the overlaid catalytic cleft of the PKAc-SP20 binary complex (T0 structure [Gerlits et al., 2014] is shown in orange) with the T1, T2, and T3 structures from the present work. See also Figure S3. Structure 2015 23, 2331-2340DOI: (10.1016/j.str.2015.10.005) Copyright © 2015 Elsevier Ltd Terms and Conditions

Figure 4 T3 Michaelis Complex and TS Mimic Active Sites Active site of the T3 S21B structure (yellow sticks with green Mg2+ ions and water oxygens in red) superimposed onto the TS mimic structure (PDB: 1L3R; Madhusudan et al., 2002; thin gray sticks with Mg2+ in purple and water oxygens in gray). See also Figure S4. Structure 2015 23, 2331-2340DOI: (10.1016/j.str.2015.10.005) Copyright © 2015 Elsevier Ltd Terms and Conditions