Download citation
Acta Cryst. (2014). A70, C614
Download citation

link to html
Up until now, comparatively few structures were solved by native SAD. Recent advances in multi crystal averaging [1] have shown that native SAD can be applied to an increasing number of cases. Though theoretically possible [2], successful structure solutions from twinned data have not been reported yet. Here, we report the structure solution of the human Centromere protein M from a merohedrally twinned crystal with a twinning fraction of 0.45 in the space group P3. The data were collected at the bending magnet beamline X06DA at the Swiss Light Source, which is equipped with the in-house developed multi-axis goniometer PRIGo and the PILATUS 2M detector. A highly redundant 2.2 Å dataset was collected in a number of different crystal orientations. A substructure solution could only be obtained after 50000 SHELXD [3] tries. Automatic model building after phasing and density modification resulted in a model with the majority of residues built correctly. We will present this particularly difficult case together with other more routine cases, all solved with the same experimental setup and at the beamline X06DA.

Download citation
Acta Cryst. (2014). A70, C1597
Download citation

link to html
Entomopoxviruses (EV) produce two types of microcrystals in infected cells: virus-containing spheroids representing their main infectious form; and spindles, bipyramidal crystals of the viral fusolin protein, that contribute to the oral virulence of these viruses. In co-feeding experiments, spindles also enhance the insecticidal activity of unrelated insect pathogens, which suggested their use as bioinsecticide additives. To understand how fusolin contributes to virulence and assembles in vivo, we determined the structures of EV spindles by X-ray microcrystallography using crystals isolated from EV-infected common cockchafers. This structure reveals that fusolin is composed of a fibronectin III domain followed by an extended C-terminal molecular arm (CT). The globular domain is structurally homologous to CBP21, a protein that is secreted by Gram-negative bacteria to degrade chitin as a source of energy. Like CBP21, fusolin has all the hallmarks of a lytic polysaccharide monooxygenase enzyme (LPMOs) with two conserved histidine residues forming a copper binding site and a prominent di-tryptophan motif positioned to bind the planar surface of crystalline chitin. The LPMO domain assembles in vivo into ultra-stable crystals crosslinked by CT. This molecular arm mediates the formation of domain-swapped dimers and their assembly into a crystalline lattice stabilized by a 3-D network of inter-dimer disulfide bonds. Overall, the molecular organization of spindles indicates a mode of action where controlled released of the LPMO domain of fusolin by proteolytic removal of the CT extension leads to disruption of the chitin-rich peritrophic matrix of larvae to facilitate the initial steps of viral invasion of the host.

Download citation
Acta Cryst. (2014). A70, C1731
Download citation

link to html
The three macromolecular crystallography (MX) beamlines at the Swiss Light Source (SLS) rank among the most productive in Europe. The very successful design of the first beamline, X06SA, inaugurated in 2001, was the basis for the second beamline, X10SA, operated by the Paul Scherrer Institut and financed by the partners Max Planck Society, Novartis and Hofmann-La Roche. To keep up with the increasing demand for high throughput crystallographic experiments, especially in an industrial environment, as well as the rising interest in more challenging targets, the beamline is under constant development. Here we will present the recent advances in usability and performance, including software integration and automation with the completely new data acquisition software DA+, in-situ screening for diffraction candidates, (serial) micro-crystallography with micro-beam, and beamline hardware.
Follow Acta Cryst. A
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds