Salmonella Typhimurium ATCC14028 fimZ mutant. Salmonella enterica subsp. enterica serovar Typhimurium str. LT2

Fimbriae are hair-like structures present on the outer membrane of many Enterobacteriaceae and such appendages are proposed to play a significant role in the attachment of the bacteria to host cells and tissues. Salmonella enterica serovar Typhimurium has the potential to produce 13 different fimbrial types, among which type 1 fimbriae is the most common found. Expression of type 1 fimbriae is cooperatively controlled by fimZ, fimY, stm0551, fimW, and fimU within the fim gene cluster. FimZ belongs to the response regulator of the two-component regulatory system in bacteria and functions as a DNA binding protein. FimZ is a positive regulator for type 1 fimbrial expression in S. Typhimurium. A fimZ mutant in ATCC 14028 strain constructed by allelic exchange did not produce type 1 fimbriae. Total RNA was extracted from the parental ATCC 14028 and its fimZ mutant cultured in static broth and analyzed by hybridization to a S. Typhimurium LT2 DNA microarray. Transcriptomic analysis indicated that the type 1 fimbriae related genes, multidrug efflux protein gene acrF were down-regulated, whereas flagella associated genes, chemotaxis and virulence genes such as invF and invH genes were up-regulated in the fimZ mutant strain. It is possible that FimZ protein may play a role to interact with other genes besides regulating type 1 fimbriae. Overall design: RNA transcript of Salmonella Typhimurium ATCC14028 strain comparing wild-type with fimZ mutant. Two-cindition experiment, wild-type vs. fimZ mutant strain.