Browsing by Subject "vgrG-geenit"

Pectobacterium atrosepticum is a bacterium that is a causative agent of blackleg and soft rot of potatoes at temperate climate zone. The genome of P. atrosepticum was sequenced at 2004. Sequence revealed six vgrG genes, and five of them are predicted to encode for proteins having uncharacterized function. VgrG proteins are found to be secreted by a novel secretion system called type VI secretion. They are also suggested to be a part of the type VI secretion translocon. VgrG proteins are presumed to be cytotoxic to the hosts of pathogenic bacteria. A mutation in a vgrG gene attenuates virulence of a few human and animal pathogenic bacteria. The aim of this study was to find out the affect of vgrG genes to the virulence of P. atrosepticum. In this study, transcription of vgrG genes of P. atrosepticum was measured by a real-time reverse transcriptase PCR. P. atrosepticum was grown in a virulence gene inducing conditions. Most active vgrG genes were deleted by Red recombinase using method. Each mutant strain carried deletion in one of the active vgrG genes. Virulence of the mutant strains was assessed on potato tubers, according to their ability to rot tissue. Three vgrG genes were induced in bacteria when they grew in the host tissue. vgrG genes were most active in samples, which were taken from stems 96 hours after inoculation. One mutant strain was slightly more virulent (P = 0,0077). Two strains were slightly less virulent, but results were not statistically significant (P > 0,05). According to the profile of transcription, vgrG genes might be novel virulence genes. However, virulence essays did not support that possibility. In fact, one of the mutations increased the virulence of P. atrosepticum. It is possible that other vgrG genes cover the function of the deleted gene. There is no clear evidence that vgrG genes or the type VI secretion are novel virulence determinants of P. atrosepticum. Perhaps they have some other function in the active stage of the infection. Example, they might protect P. atrosepticum from competitive microbes in the rotten potato tissue.