Expression, purification and crystallization of a lyssavirus matrix (M) protein

The matrix ( M) proteins of lyssaviruses ( family Rhabdoviridae) are crucial to viral morphogenesis as well as in modulating replication and transcription of the viral genome. To date, no high-resolution structural information has been obtained for full-length rhabdovirus M. Here, the cloning, expression and purification of the matrix proteins from three lyssaviruses, Lagos bat virus ( LAG), Mokola virus and Thailand dog virus, are described. Crystals have been obtained for the full-length M protein from Lagos bat virus ( LAG M). Successful crystallization depended on a number of factors, in particular the addition of an N-terminal SUMO fusion tag to increase protein solubility. Diffraction data have been recorded from crystals of native and selenomethionine-labelled LAG M to 2.75 and 3.0 angstrom resolution, respectively. Preliminary analysis indicates that these crystals belong to space group P6(1)22 or P6(5)22, with unit-cell parameters a = b = 56.9-57.2, c = 187.9-188.6 angstrom, consistent with the presence of one molecule per asymmetric unit, and structure determination is currently in progress.