title: Regulation of the expression of prtW::gusA fusions in Erwinia carotovora subsp. carotovora.
abstract: Erwinia carotovora subsp. carotovora, a Gram-negative phytopathogenic bacterium, secretes an extracellular metalloprotease, PrtW. Previous results demonstrated that protease activity is necessary for the normal progression of disease symptoms caused by this bacterium. The present study revealed that the prtW gene constitutes an independent transcriptional unit. It is demonstrated that introduction of the prtW(+) plasmid in trans into the prtW(-) mutant restores the protease activity in this strain. Gene fusions to the gusA (beta-glucuronidase) reporter were employed to analyse the transcription of prtW. The transcription of prtW is dependent on many environmental signals. When the bacteria were grown in the presence of potato extract, the expression of the protease gene was markedly higher at the beginning of the exponential phase of growth than that observed when cells were grown in the presence of polygalacturonate (PGA). Analysis of the promoter revealed that an essential regulatory region resided between 371 and 245 bp 5' of the translational start site. As this sequence showed no homology to the KdgR box it may be involved in the binding of an unknown negative regulator protein in E. carotovora subsp. carotovora. The differential responses of prtW expression to potato extract and to PGA appeared to be dependent on the KdgR repressor and the response regulator ExpA. According to the results presented here, it is conceivable that the multiple regulatory network allows flexibility in the expression of the prtW gene during different stages of infection.
authors.affiliation: Department of Genetics Institute of Molecular and Cell Biology, Tartu University Estonian Biocentre, Riia 23, Tartu 51010, Estonia1.
authors.forename: Reet
authors.initials: R
authors.lastname: Marits
authors.affiliation: Department of Genetics Institute of Molecular and Cell Biology, Tartu University Estonian Biocentre, Riia 23, Tartu 51010, Estonia1.
authors.forename: Marina
authors.initials: M
authors.lastname: Tshuikina
authors.affiliation: Department of Plant Biology, Swedish University of Agricultural Sciences (SLU), PO Box 7080, SE-75007 Uppsala, Sweden2.
authors.forename: Minna
authors.initials: M
authors.lastname: Pirhonen
authors.affiliation: Department of Genetics Institute of Molecular and Cell Biology, Tartu University Estonian Biocentre, Riia 23, Tartu 51010, Estonia1.
authors.forename: Eve
authors.initials: E
authors.lastname: Laasik
authors.affiliation: Department of Genetics Institute of Molecular and Cell Biology, Tartu University Estonian Biocentre, Riia 23, Tartu 51010, Estonia1.
authors.forename: Andres
authors.initials: A
authors.lastname: Mäe
mesh_terms: D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D005966:Glucuronidase / Q000235:genetics* / Q000378:metabolism; D008666:Metalloendopeptidases / Q000235:genetics* / Q000378:metabolism; D016973:Pectobacterium carotovorum / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010935:Plant Diseases / Q000382:microbiology; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D011993:Recombinant Fusion Proteins; D005966:Glucuronidase; D008666:Metalloendopeptidases