lacZ fusions to genes that specify exported proteins: A general technique

E. Tapio Palva, Thomas J. Silhavy

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11 Scopus citations


We have devised a general, one-step technique for isolation of strains in which the gene coding for an exported protein is fused to the gene for β-galactosidase (lacZ). These fusions specify a hybrid protein comprised of an NH2-terminal portion of the exported protein and a large functional COOH-terminal portion of β-galactosidase. The fusions are constructed with a derivative of the Mu dII(lac, Ap) phage. To overcome the lethality that is often associated with the expression of such a hybrid gene, we have recombined an early lacZ nonsense mutation onto this phage. With the use of strains that carry a temperaturesensitive nonsense suppressor, expression of the full-length hybrid protein can be controlled by varying the growth temperature. We demonstrated the utility of this technique by isolating a series of fusions to a gene, ompA, coding for a major outer membrane protein. As expected, strains containing these fusions are not viable under conditions that permit synthesis of a functional nonsense suppressor. Accordingly, this method should also be useful for direct selection of export-defective mutants.

Original languageEnglish (US)
Pages (from-to)388-394
Number of pages7
JournalMGG Molecular & General Genetics
Issue number3
StatePublished - May 1984
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Genetics


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