Abstract
The mouse dihydrofolate reductase gene and a segment of the
Escherichia coli trp operon are expressed in
Bacillus subtilis when cloned in the “expression plasmid” pPL608. The cloned mouse gene confers trimethoprim resistance on
B. subtilis and the cloned
trp fragment complements mutations in the
B. subtilis trpD,
C and
F genes. Expression of both cloned fragments is dependent on a promoter present in the vector plasmid. The
E. coli
trp fragment is cloned in a
HindIII site within a chloramphenicol acetyltransferase gene present on pPL608, and as a result, expression of the
E. coli trpC gene product is inducible by chloramphenicol. The mouse gene is inserted at a
PstI site preceding the chloramphenicol acetyltransferase gene and its expression is not chloramphenicol inducible. The replication functions and neomycin-resistance of pPL608 are derived from pUB110. Accordingly, pPL608 is stably maintained at high copy number in
B. subtilis.