Crystallographic analysis of NosA, which catalyzes terminal amide formation in the biosynthesis of nosiheptide

Nosiheptide is a member of the thiopeptide family of antibiotics which demonstrates potent activities against various bacterial pathogens. The formation of its C‐terminal amide is catalysed by NosA in an unusual strategy for maturating certain thiopeptides by processing precursor peptides featuring a serine extension. Here, a recombinant C‐terminally truncated selenomethionine‐derivatized NosA 1–111 variant from Streptomyces actuosus consisting of residues 1–111, named SeMet NosA 1–111 , was crystallized using the sitting‐drop vapour‐diffusion method. Diffraction data were collected to 2.40 Å resolution using synchrotron radiation. The crystals belonged to the primitive cubic space group P 4 1 32, with unit‐cell parameters a = b = c = 143.3 Å. Assuming the presence of three molecules in the asymmetric unit, the calculated Matthews coefficient was 3.94 Å 3  Da −1 and the corresponding solvent content was 40.3%.