Cell lysis of Gram-negative bacteria can be efficiently achieved by expression of the cloned lysis gene E of bacteriophage PhiX174. Gene E expression is tightly controlled by the rightward lambda pR promoter and the temperature-sensitive repressor cI857 on lysis plasmid pAW12. The resulting empty bacterial cell envelopes, called bacterial ghosts, are currently under investigation as candidate v...

A 2.9 kb DNA fragment carrying the Escherichia coli proBA region, which encodes the first two enzymes of the proline biosynthetic pathway, was subcloned onto an expression plasmid carrying both the bacteriophage lambda PL promoter (lambda PL) and the lambda gene encoding a thermolabile cI repressor protein (cI857). Derepression of the lambda PL promoter by thermal inactivation of the cI857 repr...

In directed evolution, a high-throughput screening system is often a prerequisite for sampling the enzyme variants. When the target enzyme is expressed intracellularly, for example when Escherichia coli is used as the host, chemical or enzymatic disruption of cell membrane is often required in many cases, which can be tedious, time-consuming, and costly. In this study, a set of heat-inducible a...

A self-regulated high-copy number plasmid containing chloramphenicol resistant gene, for the production of recombinant proteins under the regulation of bacteriophage λpL promoter, was constructed. The designed 5024 base pair expression plasmid contained a heat sensitive repressor cI857 coding gene to regulate the function of λpL promoter under heat shock induction. Using the constructed vector,...

a self-regulated high-copy number plasmid containing chloramphenicol resistant gene, for the production of recombinant proteins under the regulation of bacteriophage ?pl promoter, was constructed. the designed 5024 base pair expression plasmid contained a heat sensitive repressor ci857 coding gene to regulate the function of ?pl promoter under heat shock induction. using the constructed vector,...

A self-regulated high-copy number plasmid containing chloramphenicol resistant gene, for the production of recombinant proteins under the regulation of bacteriophage ?pL promoter, was constructed. The designed 5024 base pair expression plasmid contained a heat sensitive repressor cI857 coding gene to regulate the function of ?pL promoter under heat shock induction. Using the constructed vector,...

The Escherichia coli gene for folylpolyglutamate synthetase-dihydrofolate synthetase was localized to plasmids pLC22-45, 24-31, and 28-44 of the Clarke-Carbon E. coli colony bank (Clarke, L., and Carbon, J. (1976) Cell 9, 91-99) by screening the bank by replica mating with an E. coli folC mutant. The folC gene was subcloned from pLC22-45 and inserted into a high copy number plasmid containing t...

An Escherichia coli DNA fragment containing the structural gene serU132 for the nonsense suppressor tRNASer2am was identified and purified by being cloned into a plasmid vector. Information obtained from DNA sequence analysis was used to select a serU132 fragment for insertion downstream from the bacteriophage lambda pL promoter in two pBR322-lambda derivatives. In nonsense mutant strains beari...

We report the construction of two vectors for Escherichia coli: pUC72, for molecular cloning, and pPLT7, for thermal-induced expression. The main feature of pUC72 is a novel polylinker region that includes restriction sites for Nde I and Nco I which provide an ATG codon for proper translation initiation of expressed genes. Vector pPLT7 is ideal for thermo-inducible expression in host cells that...