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J. Bacteriol., 07 1995, 4121-4130, Vol 177, No. 14
LM Guzman, D Belin, MJ Carson and J Beckwith
We have constructed a series of plasmid vectors (pBAD vectors) containing
the PBAD promoter of the araBAD (arabinose) operon and the gene encoding
the positive and negative regulator of this promoter, araC. Using the phoA
gene and phoA fusions to monitor expression in these vectors, we show that
the ratio of induction/repression can be 1,200-fold, compared with 50-fold
for PTAC-based vectors. phoA expression can be modulated over a wide range
of inducer (arabinose) concentrations and reduced to extremely low levels
by the presence of glucose, which represses expression. Also, the kinetics
of induction and repression are very rapid and significantly affected by
the ara allele in the host strain. Thus, the use of this system which can
be efficiently and rapidly turned on and off allows the study of important
aspects of bacterial physiology in a very simple manner and without changes
of temperature. We have exploited the tight regulation of the PBAD promoter
to study the phenotypes of null mutations of essential genes and explored
the use of pBAD vectors as an expression system.
Copyright © 1995, American Society for Microbiology
Tight regulation, modulation, and high-level expression by vectors containing the arabinose PBAD promoter
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
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