Crystallization and preliminary X-ray crystallographic analysis of the sclerostin-neutralizing Fab AbD09097

The secreted cystine-knot protein sclerostin was first identified from genetic screening of patients suffering from the rare bone-overgrowth diseases sclerosteosis and van Buchem disease. Sclerostin acts a negative regulator of bone growth through inhibiting the canonical Wnt signalling cascade by binding to and blocking the Wnt co-receptor LRP5/6. Its function in blocking osteoblastogenesis makes it an important target for osteoanabolic therapy approaches to treat osteoporosis, which is characterized by a progressive decrease in bone mass and density. In this work, the production, crystallization and preliminary X-ray diffraction data analysis of a sclerostin-neutralizing human Fab antibody fragment, AbD09097, obtained from a naive antibody library are reported. Crystals of the Fab AbD09097 belonged to space groupP21, with unit-cell parametersa= 45.19,b= 78.49,c= 59.20 Å, β = 95.71° and diffracted X-rays to a resolution of 1.8 Å.

High level expression of the Drosophila Toll receptor ectodomain and crystallization of its complex with the morphogen Spätzle

Drosophila Toll receptors are involved in embryonic development and in the immune response of adult flies. In both processes, the Toll receptor ligand is the NGF-like cystine knot protein Spätzle. Here we present the expression of Toll receptor ectodomain in Schneider cells at high yields and demonstrate a high affinity interaction with the refolded and trypsin-processed Spätzle cystine knot domain dimer. Poorly and anisotropically diffracting crystals of the complex could be improved by deglycosylation and dehydration, paving the way for structural analyses of the Toll-Spätzle interaction.