• Korean Journal of Microbiology
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• v.30 no.2
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• pp.134-140
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• 1992

Teh $polA^{+}$ gene can be transducted in a multicopy mini-Mu plasmid, but not cloned because the product of this gene is lethal when overproduced. Although, we obtained one surviving cell, in which the ColEl-derived mini-Mu plasmid suffered a spontaneous deletion exactly at the region where the $polA^{+}$ gene was cloned. The $PolA^{+}$ unstream flanking sequence containing the promoter and pribnow-box was delected in vivo ; consequently this gene is not able to be expressed.