Binding of adenovirus capsid to dipalmitoyl phosphatidylcholine provides a novel pathway for virus entry.

Adenovirus (Ad) is an airborne, nonenveloped virus infecting respiratory epithelium. To study the mechanism of Ad entry, we used alveolar adenocarcinoma A549 cells, which have retained the ability of alveolar epithelial type II cells to synthesize the major component of pulmonary surfactant, disaturated phosphatidylcholine. Stimulation of phosphatidylcholine secretion by calcium ionophore or phorbol ester augmented the susceptibility of these cells to Ad.

Antibody inhibition of the transcriptase activity of the rotavirus DLP: a structural view.

On entering the host cell the rotavirus virion loses its outer shell to become a double-layered particle (DLP). The DLP then transcribes the 11 segments of its dsRNA genome using its own transcriptase complex, and the mature mRNA emerges along the 5-fold axis. In order to better understand the transcription mechanism and the role of VP6 in transcription we have studied three monoclonal antibodies against VP6: RV-238 which inhibits the transcriptase activity of the DLP; and RV-133 and RV-138 which have no effect on transcription.

When two into one won't go: fitting in the presence of steric hindrance and partial occupancy.

Combining structural data from cryo-electron microscopy (cryo-EM) and X-ray crystallography to give pseudo-atomic models of large molecular complexes has proved particularly suitable for studying viruses and viral complexes. Several groups are developing programs to fit X-ray data to EM data. These programs are in general tailored to particular problems with regard to size, symmetry, number of rigid bodies, resolution etc.

Projection structure of a transcriptional regulator, HupR, determined by electron cryo-microscopy.

Large, well-ordered two-dimensional crystals of the histidine-tagged-HupR protein, a transcriptional regulator from the photosynthetic bacterium Rhodobacter capsulatus, were obtained by specific interaction with a Ni(2+)-chelated lipid monolayer. HupR is a response regulator of the NtrC subfamily; it activates the transcription of the structural genes hupSLC, of [NiFe]hydrogenase. A projection map of the full-length protein at 9 A resolution was obtained by electron cryo-microscopy and image analysis of frozen-hydrated two-dimensional crystals.

Bivalent binding of a neutralising antibody to a calicivirus involves the torsional flexibility of the antibody hinge.

The structure of a complex between rabbit haemorrhagic disease virus (RHDV) virus-like particles (VLPs) and a neutralising monoclonal antibody mAb-E3 has been determined at low resolution by cryo-electron microscopy and three-dimensional (3-D) reconstruction techniques. The atomic co-ordinates of an Fab were fitted to the cryo-electron microscope density map to produce a binding model. The VLP has a T = 3 icosahedral lattice consisting of a hollow spherical shell with 90 protruding arches.