title: An ordered water channel in Staphylococcus aureus FabI: unraveling the mechanism of substrate recognition and reduction.
abstract: One third of all drugs in clinical use owe their pharmacological activity to the functional inhibition of enzymes, highlighting the importance of enzymatic targets for drug development. Because of the close relationship between inhibition and catalysis, understanding the recognition and turnover of enzymatic substrates is essential for rational drug design. Although the Staphylococcus aureus enoyl-acyl carrier protein reductase (saFabI) involved in bacterial fatty acid biosynthesis constitutes a very promising target for the development of novel, urgently needed anti-staphylococcal agents, the substrate binding mode and catalytic mechanism remained unclear for this enzyme. Using a combined crystallographic, kinetic, and computational approach, we have explored the chemical properties of the saFabI binding cavity, obtaining a consistent mechanistic model for substrate binding and turnover. We identified a water-molecule network linking the active site with a water basin inside the homo-tetrameric protein, which seems to be crucial for the closure of the flexible substrate binding loop as well as for an effective hydride and proton transfer during catalysis. On the basis of our results, we also derive a new model for the FabI-ACP complex that reveals how the ACP-bound acyl-substrate is injected into the FabI binding crevice. These findings support the future development of novel FabI inhibitors that target the FabI-ACP interface leading to the disruption of the interaction between these two proteins.
authors.affiliation: †Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany.|‡Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Wuerzburg, Josef-Schneider-Str. 2, D-97080 Wuerzburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Schiebel
authors.forename: Andrew
authors.initials: A
authors.lastname: Chang
authors.affiliation: †Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Merget
authors.forename: Gopal R
authors.initials: GR
authors.lastname: Bommineni
authors.forename: Weixuan
authors.initials: W
authors.lastname: Yu
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Spagnuolo
authors.forename: Michael V
authors.initials: MV
authors.lastname: Baxter
authors.affiliation: ‡Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Wuerzburg, Josef-Schneider-Str. 2, D-97080 Wuerzburg, Germany.
authors.forename: Mona
authors.initials: M
authors.lastname: Tareilus
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Tonge
authors.affiliation: ‡Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Wuerzburg, Josef-Schneider-Str. 2, D-97080 Wuerzburg, Germany.
authors.forename: Caroline
authors.initials: C
authors.lastname: Kisker
authors.affiliation: †Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany.
authors.forename: Christoph A
authors.initials: CA
authors.lastname: Sotriffer
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D002384:Catalysis; D020134:Catalytic Domain; D050753:Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / Q000737:chemistry*; D008958:Models, Molecular; D013211:Staphylococcus aureus / Q000201:enzymology*; D013329:Structure-Activity Relationship; D014867:Water / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D014867:Water; D050753:Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)