IMPROVED SHUTTLE VECTORS FOR HALOFERAX-VOLCANII INCLUDING A DUAL-RESISTANCE PLASMID

Two new Haloferax-Escherichia shuttle vectors are described, pMDS20 an d pMLH3. These vectors contain the E. coli ColE1 plasmid ori region an d ampicillin-resistance(Ap(R))-conferring bla gene, and the Haloferax pHK2 replicon region and novobiocin-resistance(Nb-R)-encoding gyrB gen e, enabling maintenance and selection in both hosts. Plasmid pMLH3 has , in addition, a H. volcanii mevinolin-resistance (Mv(R)) determinant and restriction sites allowing insertional inactivation of either mark er, to facilitate the identification of Haloferax transformants harbou ring cloned sequences. Sequencing of gyrA, within the Nb-R determinant , and the pHK2 ori region has been completed so the complete sequence of both pMDS20 and pMLH3 is now known.