1887

Abstract

Summary

To study the effect of gene dosage on gene expression, λp5I857293, a replication defective lambda phage carrying part of the operon (containing the promoter, operator and gene) in the b2 region was studied in strain JC6256 where the operon is deleted and at a temperature where the λ repressor is inactive. In measuring the synthesis of β-galactosidase, it was possible to separate the effects of the promoter from those of the phage promoter. When the synthesis of β-galactosidase was initiated from the inserted promoter in JC6256(λ) in the presence of additional cyclic AMP, the rate and level of β-galactosidase synthesis were directly proportional to the multiplicity of infection (gene dosage). Furthermore, β-galactosidase synthesis was initiated about 5 min after infection, just as with isopropyl-β--thiogalactoside (IPTG) induction.

When the synthesis of β-galactosidase was initiated from the phage promoter in JC6256 in the absence of additional cyclic AMP, the rate and level of β-galactosidase synthesis were again linearly proportional to gene dosage. On the other hand, initiation of β-galactosidase synthesis was delayed until 10 to 20 min after infection. These results suggest that: (i) in the absence of negative controlling factors, the extent of gene expression is proportional to gene dosage; (ii) varying the gene dosage can be used to regulate gene expression.

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/content/journal/jgv/10.1099/0022-1317-58-2-297
1982-02-01
2019-11-18
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http://instance.metastore.ingenta.com/content/journal/jgv/10.1099/0022-1317-58-2-297
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