High-resolution structures of the d-alanyl carrier protein (Dcp) DltC from Bacillus subtilis reveal equivalent conformations of apo- and holo-forms

d-Alanylation of lipoteichoic acids plays an important role in modulating the properties of Gram-positive bacteria cell walls. The d-alanyl carrier protein DltC from Bacillus subtilis has been solved in apo- and two cofactor-modified holo-forms, whereby the entire phosphopantetheine moiety is defined in one. The atomic resolution of the apo-structure allows delineation of alternative conformations within the hydrophobic core of the 78 residue four helix bundle. In contrast to previous reports for a peptidyl carrier protein from a non-ribosomal peptide synthetase, no obvious structural differences between apo- and holo-DltC forms are observed. Solution NMR spectroscopy confirms these findings and demonstrates in addition that the two forms exhibit similar backbone dynamics on the ps-ns and ms timescales.