Volume 17, Issue 7, Pages 776-785 (July 2010) Recognition of Intermediate Functionality by Acyl Carrier Protein over a Complete Cycle of Fatty Acid Biosynthesis  Eliza Płoskoń, Christopher J. Arthur, Amelia L.P. Kanari, Pakorn Wattana-amorn, Christopher Williams, John Crosby, Thomas J. Simpson, Christine L. Willis, Matthew P. Crump  Chemistry & Biology  Volume 17, Issue 7, Pages 776-785 (July 2010) DOI: 10.1016/j.chembiol.2010.05.024 Copyright © 2010 Elsevier Ltd Terms and Conditions

Chemistry & Biology 2010 17, 776-785DOI: (10. 1016/j. chembiol. 2010 Copyright © 2010 Elsevier Ltd Terms and Conditions

Figure 1 Generalized Scheme of the FAS Catalytic Cycle (A) The reaction is initiated by the transfer of the acyl moiety to the ketosynthase, catalyzed by the acetyl-CoA-ACP transacylase (AT) and the malonyl moiety to ACP catalyzed by malonyl-CoA-ACP transacylase (MAT). The ketosynthase (KS) catalyzes the decarboxylative condensation of the acyl intermediate with malonyl-ACP to yield the 3-oxoacyl-ACP. This reaction is followed by reduction of the β-keto group by the ketoreductase (KR). The resulting 3-hydroxyacyl-ACP is dehydrated by a dehydratase (DH) to 2-enoyl-ACP, which is reduced by the enoylreductase (ER) to the fully saturated acyl substrate for further cyclic elongation. The reaction proceeds until the desired chain length is produced, which is than released from the ACP by the thioesterase (TE). (B) Synthetic summary for 3-oxooctanyl-ACP, (C) 3R-hydroxyoctanoyl-ACP, and (D) 2-octenoyl-ACP. The numbering indicated for 4′-PP group is used in the text. Chemistry & Biology 2010 17, 776-785DOI: (10.1016/j.chembiol.2010.05.024) Copyright © 2010 Elsevier Ltd Terms and Conditions

Figure 2 Comparison of the 1H-15N HSQC Spectra of the Derivatized ACPs (A) Superimposed 1H-15N HSQC spectra of uniformly 15N-labeled forms of S. coelicolor ACP. Shown are hexanoyl-ACP (pink), 3-oxooctanyl-ACP (gray), 3R-hydroxyoctanoyl-ACP (blue), 2-octenoyl-ACP (yellow), and octanoyl-ACP (red). (B) Chemical shift perturbations (δΔav) versus holo ACP plotted against residue number. The primary sequence of S. coelicolor FAS ACP and the positions of the α-helices are indicated. See also Figure S1. Chemistry & Biology 2010 17, 776-785DOI: (10.1016/j.chembiol.2010.05.024) Copyright © 2010 Elsevier Ltd Terms and Conditions

Figure 3 Structural Ensembles for the Best Fit Superposition of the Backbone (N, Cα, C) Atoms of the 20 Simulated Annealing Structures (A) Hexanoyl-ACP (pink), (B) 3-oxooctanyl-ACP (gray), (C) 3R-hydroxyoctanoyl-ACP (blue), (D) 2-octenoyl-ACP (yellow), and (E) octanoyl-ACP (red). The protein backbone is presented in lines as well as phosphopantetheine attachment. In all five cases, the superposition was made on the closest to average structure in the ensemble of 20 models over residues 4–18, 42–53, 60–65, and 70–79. Chemistry & Biology 2010 17, 776-785DOI: (10.1016/j.chembiol.2010.05.024) Copyright © 2010 Elsevier Ltd Terms and Conditions

Figure 4 The Hydrophobic Pocket of Octanoyl-ACP The closest to average structure of octanoyl-ACP (in ribbon, acyl attachment in sticks) with the key residues defining the hydrophobic pocket presented in sticks. Chemistry & Biology 2010 17, 776-785DOI: (10.1016/j.chembiol.2010.05.024) Copyright © 2010 Elsevier Ltd Terms and Conditions

Figure 5 The Overall Folds of Derivatized ACP Forms (top) and Details of the 4′-PP Conformation (bottom) The closest to average structures are shown in ribbon (protein backbone) and sticks (4′-PP chain). (A) hexanoyl-ACP (pink); (B) 3-oxooctanyl-ACP (gray); (C) 3R-hydroxyoctanoyl-ACP (blue); (D) 2-octenoyl-ACP (yellow), and (E) octanoyl-ACP (red). Structures are presented aligned as described in the text. Chemistry & Biology 2010 17, 776-785DOI: (10.1016/j.chembiol.2010.05.024) Copyright © 2010 Elsevier Ltd Terms and Conditions

Figure 6 Comparison of the Closest to Average Acyl ACP Structures The most significant changes are indicated in black (for protein) and red (for 4′-PP) arrows. Stereoviews are shown for (A) hexanoyl- versus 3-oxooctanyl-ACP, (B) 3-oxooctanyl- versus 3R-hydroxyoctanoyl-ACP; (C) 3R-hydroxyoctanoyl- versus 2-octenoyl-ACP; (D) 2-octenoyl- versus octanoyl-ACP, and (E) hexanoyl- versus octanoyl-ACP. Structures were aligned as described in the text and the color scheme is identical to Figure 6. The right-hand column shows a graphical depiction of the change in chain burial depending on the attached intermediate. The dotted line represents the hydrophobic binding cavity of the fatty acid ACP and the changing position of carbon 1 and carbon 3 is indicated. Chemistry & Biology 2010 17, 776-785DOI: (10.1016/j.chembiol.2010.05.024) Copyright © 2010 Elsevier Ltd Terms and Conditions

Figure 7 Structural Comparison of acylated E. coli and S. coelicolor FAS ACPs Comparison of E. coli hexanoyl-ACP (A) structure with S. coelicolor (B) hexanoyl-ACP. The protein chain is shown as a ribbon and the acyl-phosphopantetheine is shown in stick representation. Structures have been aligned with one another and presented with helix II toward the reader. Chemistry & Biology 2010 17, 776-785DOI: (10.1016/j.chembiol.2010.05.024) Copyright © 2010 Elsevier Ltd Terms and Conditions