TABLE 3.
Location of mutation(s) | Plasmid | hrpII box and flanking region sequenceb | β-Galactosidase activity (Miller units [SD])c
|
Induction ratiod | |
---|---|---|---|---|---|
Wild type | hrpB | ||||
5 10 15 20 25 30 | |||||
....|....|....|....|....|....|.... | |||||
Flanking sequences | pSC152 | TTCGTACGCTTGCACAAGGTTTCGGGGCAGCGG | 728 (49) | 18 (1) | 40.4 |
pCZ475 | ........................A........ | 155 (5) | 20 (1) | 7.8 | |
pCZ472 | ....A............................ | 91 (8) | 18 (2) | 5.1 | |
pCZ473 | ..............A.................. | 372 (16) | 21 (4) | 17.7 | |
pCZ478 | ...................G............. | 583 (42) | 32 (10) | 18.2 | |
pCZ474 | .......CT.GTGC..GC............... | 371 (25) | 17 (1) | 21.8 | |
Repeat spacing | pCZ444 | TTCGTA--CTTGCACAAGGTTTCGGGGCAGCGG | 15 (2) | 16 (1) | 0.9 |
pCZ460 | TTCGTAC-CTTGCACAAGGTTTCGGGGCAGCGG | 54 (8) | 19 (5) | 2.8 | |
pCZ445 | TTCGTACGGCTTGCACAAGGTTTCGGGGCAGCGG | 141 (17) | 18 (1) | 7.8 | |
pCZ446 | TTCGTACGCGCTTGCACAAGGTTTCGGGGCAGCGG | 19 (3) | 20 (2) | 1.0 | |
Distance between hrpII and −10 boxes | pCZ476 | TTCGTACGCTTGCACAAGGTTTCGGATATGGCAGCGG | 21 (2) | 19 (3) | 1.1 |
pCZ494 | TTCGTACGCTTGCACAAGGTTTCGGGG---CGG | 28 (3) | 18 (3) | 1.6 |
Derivatives of the pSC152 reporter plasmid with mutations in DNA regions downstream of the hrpII box repeats of minimal hrpYp were obtained by PCR and tested for transcriptional activity in R. solanacearum.
Nucleotides in bold indicate conserved residues of hrpII box tandem repeats. Dots symbolize the conserved residues in the pSC152-derived plasmids. Dashes indicate that the corresponding nucleotide in the wild-type sequence has been deleted from the synthetic promoter construct. Underlined nucleotides have been added in the regions flanking hrpII box repeats.
β-Galactosidase activities assayed for the wild-type strain (GMI1000) and a hrpB mutant (GMI1525) are the means of at least three experiments.
Ratio of activity in the wild-type strain to activity in the hrpB mutant strain.