title: Structure-based mechanism of lipoteichoic acid synthesis by Staphylococcus aureus LtaS.
abstract: Staphylococcus aureus synthesizes polyglycerol-phosphate lipoteichoic acid (LTA) from phosphatidylglycerol. LtaS, a predicted membrane protein with 5 N-terminal transmembrane helices followed by a large extracellular part (eLtaS), is required for staphylococcal growth and LTA synthesis. Here, we report the first crystal structure of the eLtaS domain at 1.2-A resolution and show that it assumes a sulfatase-like fold with an alpha/beta core and a C-terminal part composed of 4 anti-parallel beta-strands and a long alpha-helix. Overlaying eLtaS with sulfatase structures identified active site residues, which were confirmed by alanine substitution mutagenesis and in vivo enzyme function assays. The cocrystal structure with glycerol-phosphate and the coordination of a Mn(2+) cation allowed us to propose a reaction mechanism, whereby the active site threonine of LtaS functions as nucleophile for phosphatidylglycerol hydrolysis and formation of a covalent threonine-glycerolphosphate intermediate. These results will aid in the development of LtaS-specific inhibitors for S. aureus and many other Gram-positive pathogens.
authors.affiliation: Division of Molecular Biosciences, Department of Microbiology, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.
authors.forename: Duo
authors.initials: D
authors.lastname: Lu
authors.forename: Mirka E
authors.initials: ME
authors.lastname: Wörmann
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhang
authors.forename: Olaf
authors.initials: O
authors.lastname: Schneewind
authors.forename: Angelika
authors.initials: A
authors.lastname: Gründling
authors.forename: Paul S
authors.initials: PS
authors.lastname: Freemont
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D020134:Catalytic Domain; D006868:Hydrolysis; D008070:Lipopolysaccharides / Q000096:biosynthesis*; D008345:Manganese / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D013211:Staphylococcus aureus / Q000378:metabolism*; D013682:Teichoic Acids / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D013682:Teichoic Acids; D008345:Manganese; C009900:lipoteichoic acid