To elucidate the regulatory mechanism of virE operon from vir regions (virA, virB, virC, virD, virG, virE) of pTiA6 which have been known to be essential for efficient crown gall tumorigenesis in plants, the activity of the truncated virE promoter was analyzed.
pSM358cd, a recombinant plasmid in which virE :: Tn3-HoHo1 (Tn3-promoterless lacZ) was cloned into SalⅠ site of pVK102, was digested with SalⅠ and virE :: Tn3-HoHo1 was seperated from pVK102. To construct the truncted virE recombinant plasmids (pJS031, pJS051, pJS102, pJS201, pJS301), 5´-end of virE promoter was deleted with BAL31 and cloned into pVK102 and then transferred into A. tumefaciens A348 (pTiA6).
According to the activity of the truncated virE promoter in recombinant plasmids, they were classified into two groups, pJS031, pJS051, pJS101 and pJS201 belong to a functional group and pJS301 is a non-functional. The size of deleted nucleotides of pJS201 and pJS301 seemed to be about 130 nucleotides and about 250 nucleotides from 5´-end of virE promoter, respectively. Hence it was thought that the essential site of the virE promoter was located between about 130th nucleotide and 250th nucleotide from 5´-end of the virE promoter.
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