Purification of recombinant M3 proteins of murine gammaherpesviruses 68 and 72 expressed in Escherichia coli

Abstract

M3 proteins of 44 kDa of murine gammaherpesviruses 68 and 72 (MHV-68, MHV-72) were identified as herpesvirus vCKBP-3, soluble inhibitors of the host chemokine network providing a selective advantage for the virus by inhibiting the antiviral and inflammatory response during both acute and latent infection. The MHV-72 M3 protein was found to contain a single mutation (Asp307Gly) near its chemokine-binding domain and differ from that of MHV-68 in the ability to bind some human chemokines. In this study, we optimized the expression of his-tagged M3 proteins of MHV-68 and MHV-72 in Escherichia coli and their purification by Ni-NTA chromatography under both denaturing and native conditions. The integrity of the N-terminus of the MHV-72 M3 protein was verified by partial sequencing. The results showed that E. coli is useful for the preparation of native, recombinant M3 proteins of murine gammaherpesviruses in sufficient quantity and purity for further biological studies.