Expression, purification and preliminary crystallographic analysis of Pseudomonas aeruginosa RocR protein.

Pseudomonas aeruginosa RocR, an EAL-domain protein which regulates the expression of virulence genes and biofilm formation, has been cloned and expressed in Escherichia coli and purified. Here, the crystallization and preliminary diffraction analysis of RocR are reported. The X-ray diffraction data were processed to a resolution of 2.50 A. The crystals belonged to space group P6(1)22 or P6(5)22, with unit-cell parameters a = 118.8, b = 118.8, c = 495.1 A, alpha = beta = 90, gamma = 120 degrees .

The C-terminal segment of the cysteine-rich interdomain of Plasmodium falciparum erythrocyte membrane protein 1 determines CD36 binding and elicits antibodies that inhibit adhesion of parasite-infected erythrocytes.

Attachment of erythrocytes infected by Plasmodium falciparum to receptors of the microvasculature is a major contributor to the pathology and morbidity associated with malaria. Adhesion is mediated by the P. falciparum erythrocyte membrane protein 1 (PfEMP-1), which is expressed at the surface of infected erythrocytes and is linked to both antigenic variation and cytoadherence. PfEMP-1 contains multiple adhesive modules, including the Duffy binding-like domain and the cysteine-rich interdomain region (CIDR). The interaction between CIDRalpha and CD36 promotes stable adherence of parasitized erythrocytes to endothelial cells. Here we show that a segment within the C-terminal region of CIDRalpha determines CD36 binding specificity. Antibodies raised against this segment can specifically block the adhesion to CD36 of erythrocytes infected with various parasite strains. Thus, small regions of PfEMP-1 that determine binding specificity could form suitable components of an antisequestration malaria vaccine effective against different parasite strains.

Structure of the SARS coronavirus main proteinase as an active C2 crystallographic dimer.

The 34 kDa main proteinase (Mpro) from the severe acute respiratory syndrome coronavirus (SARS-CoV) plays an important role in the virus life cycle through the specific processing of viral polyproteins. As such, SARS-CoV Mpro is a key target for the identification of specific inhibitors directed against the SARS virus. With a view to facilitating the development of such compounds, crystals were obtained of the enzyme at pH 6.5 in the orthorhombic space group P2(1)2(1)2 that diffract to a resolution of 1.9 A. These crystals contain one monomer per asymmetric unit and the biologically active dimer is generated via the crystallographic twofold axis. The conformation of the catalytic site indicates that the enzyme is active in the crystalline form and thus suitable for structure-based inhibition studies.