title: Crystal structure of DltA. Implications for the reaction mechanism of non-ribosomal peptide synthetase adenylation domains.
abstract: DltA, the D-alanine:D-alanyl carrier protein ligase responsible for the initial step of lipoteichoic acid D-alanylation in Gram-positive bacteria, belongs to the adenylation domain superfamily, which also includes acetyl-CoA synthetase and the adenylation domains of non-ribosomal synthetases. The two-step reaction catalyzed by these enzymes (substrate adenylation followed by transfer to the reactive thiol group of CoA or the phosphopantheinyl prosthetic group of peptidyl carrier proteins) has been suggested to proceed via large scale rearrangements of structural domains within the enzyme. The structures of DltA reported here reveal the determinants for D-Ala substrate specificity and confirm that the peptidyl carrier protein-activating domains are able to adopt multiple conformational states, in this case corresponding to the thiolation reaction. Comparisons of available structures allow us to propose a mechanism whereby small perturbations of finely balanced metastable structural states would be able to direct an ordered formation of non-ribosomal synthetase products.
authors.affiliation: Institut für Biochemie und Biotechnologie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Strasse 3, D-06120 Halle/Saale, Germany.
authors.forename: Huma
authors.initials: H
authors.lastname: Yonus
authors.forename: Piotr
authors.initials: P
authors.lastname: Neumann
authors.forename: Stephan
authors.initials: S
authors.lastname: Zimmermann
authors.forename: Jürgen J
authors.initials: JJ
authors.lastname: May
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Marahiel
authors.forename: Milton T
authors.initials: MT
authors.lastname: Stubbs
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry*; D019729:Carbon-Oxygen Ligases / Q000737:chemistry*; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray / Q000379:methods; D004926:Escherichia coli / Q000378:metabolism; D008956:Models, Chemical; D008968:Molecular Conformation; D016296:Mutagenesis; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012270:Ribosomes / Q000737:chemistry; D013237:Stereoisomerism; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds
chemical_list: D001426:Bacterial Proteins; D010455:Peptides; D013438:Sulfhydryl Compounds; D019729:Carbon-Oxygen Ligases; C502532:DltA protein, Bacillus subtilis