Crystallization and preliminary X-ray analysis of the bacillaene synthase <i>trans</i>-acting acyltransferase PksC

The antibiotic bacillaene is biosynthesized in Bacillus subtilis by a hybrid type 1 modular polyketide synthase/nonribosomal peptide synthetase of the trans-acyltransferase (trans-AT) class. Within this system, the essential acyl-group loading activity is provided by the action of three free-standing trans-acting acyltransferases. Here, the recombinant expression, purification and crystallization of the bacillaene synthase trans-acting acyltransferase PksC are reported. A diffraction data set has been collected from a single PksC crystal to 1.44 Å resolution and the crystal was found to belong to the orthorhombic space group P2(1)2(1)2(1)

Structural properties of a viral orthologue of cellular CD200 protein: KSHV vOX2

AbstractKaposi׳s sarcoma-associated herpesvirus (KSHV) vOX2 is a cell surface glycoprotein expressed during viral lytic replication to suppress host inflammatory reactions. Here we have characterised vOX2 with biochemical, biophysical and bioinformatics tools and as a result propose a 3-dimensional model for vOX2 based on structural and functional homology with the PD-L1 protein. To validate this model, vOX2 was characterised by analytical ultracentrifugation (AUC) and circular dichroism spectroscopy (CD). The results identified the potential glycosylation sites and revealed that vOX2 is predominantly a beta-folded molecule with an RGD adhesion motif exposed on the C-terminal domain. The protein exists in monomer–dimer equilibrium similar to its IgV-type folded homologues, with 30–36% glycosylation and the molecular weight of the extracellular fragment of molecule is 32.0–33.6kDa, much less than 50kDa. Thus, the structural similarity to PD-L1 verifies its immunomodulatory potential and the RGD motif suggests an adhesive capacity