A shuttle expression vector, designated as pAJ, was constructed based on the Haloferax volcanii-Escherichia coli shuttle vector pSY1. This new construct contains the amyH promoter from Haloarcula hispanica and was able to confer the promoter activity in both Hfx. volcanii and E. coli. pAJ successfully expressed proteins in Hfx. volcanii or E. coli, rendering it feasible to express target proteins in corresponding domains. In addition, pAJ contains a multiple cloning site with 11 restriction sites and a 6×His tag sequence, and the vector size w...