Medycyna Wet. 62 (11), 1233-1235, 2006
Mizielińska M., Nawrotek P. |
Molecular aspects of the lack of lactose fermentation by pathogenic Yersinia pseudotuberculosis strains |
The incapacity for lactose fermentation by Yersinia pseudotuberculosis strains is a very important diagnostic characteristic. There are only two (lacZ and lacY) genes from three known structural genes of lactose fermentation pathway present in Y. pseudotuberculosis genome. The result of the expression of gene lacZ is b-galactosidase (positive result of ONPG test). The fragment of 895229 bp includes 812 genes and unencoding regions. This fragment separates lacZ and lacY genes. That is why these genes are not regulated like in the operon. Moreover there is no regulatory gene (lacI), encoding lac repressor, and there is no lacA gene, encoding b-galactosidase transacethylase in Y. pseudotuberculosis genome. That is why lactose is not an inductor of synthesis of lactose fermentation pathway enzymes. This proves that there is no lactose operon in Y. pseudotuberculosis genome, but only its fragment. |
Keywords: Yersinia pseudotuberculosis, lactose operon, lacY gene, lacZ gene |