Solution X-ray scattering study of a full-length class A penicillin-binding protein

► We generated a model of full-length PBP1b from Streptococcus pneumoniae in solution. ► We first modeled ab initio the glycosyltransferase domain using dummy residues. ► We then used (φ, ψ) refinement starting from a homology model of full-length PBP1b. ► Both methods show that the two catalytic domains do not have any direct contact. ► Our analysis suggests the existence of interdomain mobility of limited amplitude.