MULTIPLE COPIES OF A DNA-SEQUENCE FROM PSEUDOMONAS-SYRINGAE PATHOVAR PHASEOLICOLA ABOLISH THERMOREGULATION OF PHASEOLOTOXIN PRODUCTION

作者：ROWLEY KB; CLEMENTS DE; MANDEL M; HUMPHREYS T; PATIL SS

来源：Molecular Microbiology, 1993, 8(3): 625-635.

DOI：10.1111/j.1365-2958.1993.tb01606.x

Phaseolotoxin, a phytotoxin of Pseudomonas syringae pv. phaseolicola, is produced at 18-degrees-C but not at 28-degrees-C. Here we report that a fragment (24.4 kb) cloned from the wild-type strain, which does not harbour a gene(s) involved in phaseolotoxin biosynthesis, abolishes this thermoregulation in the wild type and suppresses a Tox- mutant at both temperatures. A subclone harbouring a 485 bp fragment contains motifs that are characteristic of DNA-binding sites. In mobility shift assays we have detected a protein(s) from the wild-type and the mutant strains, grown at appropriate temperatures, that specifically binds to the fragment containing the DNA-binding motifs. We propose that the binding protein is a repressor which is 'titrated' by this fragment when it is present in the cell on a multiple copy plasmid, thus allowing expression of phaseolotoxin genes.

• 出版日期1993-5