A unique operon structure has been identified in the genomes of several plant- and insect-associated bacteria. The distinguishing feature of this operon is the presence of tandem hilA and hilB genes encoding dioxygenases belonging to the PF13640 and PF10014 (BsmA) Pfam families, respectively. The genes encoding HilA and HilB from Pantoea ananatis AJ13355 were cloned and expressed in Escherichia...

Salmonella enterica serovar typhimurium (S. typhimurium) encounters short chain fatty acids (inorganic acids containing propionate, butyrate and acetate) in the intestine as well as in food preservatives. Short chain fatty acids (SCFAs) exposed organisms have been reported to offer resistance to organic acid resulting into enhanced virulence. However, the role of hilA (hyper invasive loci) gene...

The ability of Salmonella enterica serovar Typhimurium to traverse the intestinal mucosa of a host is an important step in its ability to initiate gastrointestinal disease. The majority of the genes required for this invasive characteristic are encoded on Salmonella pathogenicity island 1 (SPI1), and their expression is controlled by the transcriptional activator HilA, a member of the OmpR/ToxR...

Signature-tagged mutagenesis is a functional genomics approach to identify bacterial virulence genes by simultaneously screening multiple mutants in a single host animal. Avirulent (attenuated) mutants are identified by negative selection (failure to colonize the host). The method was recently developed to investigate Salmonella typhimurium in a mouse model of human typhoid fever. We modified t...

Induction of invasion gene transcription and expression of the invasive phenotype of Salmonella strains are regulated by environmental conditions. Experimental evidence indicates that oxygen, pH, and osmotic conditions need to closely resemble those of the host intestinal lumen for invasion gene activation. The hilA gene, encoded on Salmonella pathogenicity island 1 (SPI-1), is a transcriptiona...

Salmonellae initiate disease through the invasion of host cells within the intestine. This ability to invade requires the coordinated action of numerous genes, many of which are found within Salmonella pathogenicity island 1 (SPI-1). The key to this process is the ability of the bacteria to respond to the environment, thereby upregulating the necessary genes under optimal conditions. Central to...

Background and Objective: Salmonellosis is an important infectious zoonotic disease that makes it even more significant to identify and control the causative strains. Molecular methods, especially polymerase chain reaction (PCR), for virulence genes can help to quickly and accurately identify Salmonella strains. Accordingly, the purpose of this study was molecular identification based on sivH, ...

Salmonella enterica serovar Typhimurium causes self-limiting gastroenteritis in humans and a typhoid-like disease in mice that serves as a model for typhoid infections in humans. A critical step in Salmonella pathogenesis is the invasion of enterocytes and M cells of the small intestine via expression of a type III secretion system, encoded on Salmonella pathogenicity island 1 (SPI-1), that sec...

Hila Hashemi,1 A. Oskooi,2 J. D. Joannopoulos,3 and Steven G. Johnson1 1Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 2Department of Electronic Science and Engineering, Kyoto University, Japan 3Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA (Received 20 February 2011; published 11 August 2...

Salmonella typhimurium invasion of nonphagocytic cells requires the expression of a type III secretion system (TTSS) encoded within Salmonella pathogenicity island 1 (SPI1). TTSS gene transcription is activated in response to environmental signals and requires transcriptional regulators encoded within (HilA) and outside (SirA) SPI1. Two unique loci, sirB and sirC, which contribute to SPI1 gene ...