AbstractsBiology & Animal Science

Rhodococcus equi is a Gram-positive soil organism that causes an aggressive bronchopneumonia in foals and opportunistic infections in immuno-compromised humans. Virulent strains possess an 80 – 90 kb plasmid that encodes an immunogenic surface-located virulence-associated protein VapA. The virulence of the organism has been largely attributed to this protein since mutants lacking vapA are attenuated for virulence in mice. VapA is an unusual lipoprotein and existing evidence suggests its biogenesis may not involve normal lipoprotein processing. In order to understand the structure of VapA and other virulence associated proteins, their genes were cloned, expressed, purified and crystallised. VapG produce high quality crystals that diffracted to 1.8 Å. The structure was resolved to be a closed β-barrel with a long unstructured N-terminus which is similar to both VapB and VapD which have also recently been characterised.