A set of integrative 'promoter probe' plasmids were constructed for bo
th translational and transcriptional fusions. The vectors are based on
the broad host range, low copy number plasmid pRK290 (IncP1) in which
the attachment site of Rhizobium phage 16-3 and the lacZ gene of Esch
erichia coli were combined, The vectors integrate into the chromosome
of Rhizobium meliloti, providing also the advantages of the single cop
y promoter probe cassettes, Thus they fulfil the prerequisite of the s
ystems used for investigating gene regulation. The plasmids were appli
ed for the study of the transcription regulation of the 16-3 phage. Th
eir versatile use is also demonstrated. (C) 1998 Published by Elsevier
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