Project description:This experiment set includes 64 arrays representing 26 serovars and strains of Salmonella spp. including many representatives of subspecies I, Arizona from subsp. IIIa, and S. bongori from subsp. V. The genomic DNA from all strains were labeled with Cy5 and hybridized against an equal amount (1.5 ug) of S. typhimurium SL1344 reference genomic DNA that was labeled with Cy3, all on an S. typhimurium SL1344 spotted DNA microarray. Most of the arrays are present in triplicate to account for variability in probe generation, hybridization, and slide quality. Several are represented in duplicate, and a few without any replicates. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set
Project description:Multidrug-resistant (MDR; resistance to >3 antimicrobial classes) Salmonella enterica serovar I 4,[5],12:i:- strains were linked to a 2015 foodborne outbreak from pork. Strain USDA15WA-1, associated with the outbreak, harbors an MDR module and the metal tolerance element Salmonella Genomic Island 4 (SGI-4). Characterization of SGI-4 revealed that conjugational transfer of SGI-4 resulted in the mobile genetic element (MGE) replicating as a plasmid or integrating into the chromosome. Tolerance to copper, arsenic, and antimony compounds was increased in Salmonella strains containing SGI-4 compared to strains lacking the MGE. Following Salmonella exposure to copper, RNA-seq transcriptional analysis demonstrated significant differential expression of diverse genes and pathways, including induction of numerous metal tolerance genes (copper, arsenic, silver, and mercury). Evaluation of swine administered elevated concentrations of zinc oxide (2,000 mg/kg) and copper sulfate (200 mg/kg) as an antimicrobial feed additive (Zn+Cu) in their diet for 4 weeks prior to and 3 weeks post-inoculation with serovar I 4,[5],12:i:- indicated that Salmonella shedding levels declined at a slower rate in pigs receiving in-feed Zn+Cu compared to control pigs (no Zn+Cu). The presence of metal tolerance genes in MDR Salmonella serovar I 4,[5],12:i:- may provide benefits for environmental survival or swine colonization in metal-containing settings.
Project description:LeuO, initially identified as a leucine regulator in Escherichia coli, has since been identified as a global regulator required for bacterial pathogenicity in a broad range of bacteria, including gram-negative pathogens, such as Salmonella, Shigella, and Vibrio; and gram-positive bacteria, such as Streptococcus pneumoniae. However, the regulatory roles and targets of LeuO vary among species. In the Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium), LeuO represses the transcription of Salmonella pathogenicity island (SPI)-1, thus diminishing the ability of the bacteria to invade host cells. However, its regulatory effect on SPI-2, essential for survival within macrophages, remains poorly understood. This study aimed to determine the regulatory role of LeuO in the intracellular persistence of S. Typhimurium. Overexpression of LeuO repressed the transcription of SPI-2 genes and accordingly decreased its protein levels. Chromatin immunoprecipitation sequencing revealed the genome-wide binding sites of LeuO in S. Typhimurium 14028 and identified a distinctive 23-nucleotide motif with high similarity to that previously discovered in E. coli. Notably, multiple LeuO-binding sites were predicted within SPI-2, primarily adjacent to the ssrA and ssrB loci. In vitro binding assays verified the high binding affinity between LeuO and three specific motifs located at positions -35 to -12 (ssrA1),+231 to +254 (ssrA2) near ssrA, and at positions -622 to -599 (ssrB3) near ssrB, relative to their transcription start sites. Furthermore, LeuO overexpression abolished the transcription of lacZ fused to the ssrA promoter containing ssrA1 and ssrA2, suggesting the direct repression of ssrA via LeuO-binding. The absence of LeuO increased the intracellular survival of S. Typhimurium within macrophages, whereas its overexpression attenuated bacterial persistence, which was presumably associated with the downregulation of SPI-2 by LeuO. This study reveals the versatile regulatory mechanisms of LeuO and underscores its pivotal role in modulating SPI-2 expression, thereby providing key insights into the fine tuning of virulence by Salmonella during systemic infection.
Project description:This experiment set includes 64 arrays representing 26 serovars and strains of Salmonella spp. including many representatives of subspecies I, Arizona from subsp. IIIa, and S. bongori from subsp. V. The genomic DNA from all strains were labeled with Cy5 and hybridized against an equal amount (1.5 ug) of S. typhimurium SL1344 reference genomic DNA that was labeled with Cy3, all on an S. typhimurium SL1344 spotted DNA microarray. Most of the arrays are present in triplicate to account for variability in probe generation, hybridization, and slide quality. Several are represented in duplicate, and a few without any replicates. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Computed