Bacterial Effector Binding to Ribosomal Protein S3 Subverts NF-κB Function

Enteric bacterial pathogens cause food borne disease, which constitutes an enormous economic and health burden. Enterohemorrhagic Escherichia coli (EHEC) causes a severe bloody diarrhea following transmission to humans through various means, including contaminated beef and vegetable products, water, or through contact with animals. EHEC also causes a potentially fatal kidney disease (hemolytic uremic syndrome) for which there is no effective treatment or prophylaxis. EHEC and other enteric pathogens (e.g., enteropathogenic E. coli (EPEC), Salmonella, Shigella, Yersinia) utilize a type III secretion system (T3SS) to inject virulence proteins (effectors) into host cells. While it is known that T3SS effectors subvert host cell function to promote diarrheal disease and bacterial transmission, in many cases, the mechanisms by which these effectors bind to host proteins and disrupt the normal function of intestinal epithelial cells have not been completely characterized. In this study, we present evidence that the E. coli O157:H7 nleH1 and nleH2 genes encode T3SS effectors that bind to the human ribosomal protein S3 (RPS3), a subunit of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcriptional complexes. NleH1 and NleH2 co-localized with RPS3 in the cytoplasm, but not in cell nuclei. The N-terminal region of both NleH1 and NleH2 was required for binding to the N-terminus of RPS3. NleH1 and NleH2 are autophosphorylated Ser/Thr protein kinases, but their binding to RPS3 is independent of kinase activity. NleH1, but not NleH2, reduced the nuclear abundance of RPS3 without altering the p50 or p65 NF-κB subunits or affecting the phosphorylation state or abundance of the inhibitory NF-κB chaperone IκBα NleH1 repressed the transcription of a RPS3/NF-κB-dependent reporter plasmid, but did not inhibit the transcription of RPS3-independent reporters. In contrast, NleH2 stimulated RPS3-dependent transcription, as well as an AP-1-dependent reporter. We identified a region of NleH1 (N40-K45) that is at least partially responsible for the inhibitory activity of NleH1 toward RPS3. Deleting nleH1 from E. coli O157:H7 produced a hypervirulent phenotype in a gnotobiotic piglet model of Shiga toxin-producing E. coli infection. We suggest that NleH may disrupt host innate immune responses by binding to a cofactor of host transcriptional complexes

NF425 Resistance Management for European Corn Borer and Bt Transgenic Corn: Refuge Design and Placement

Factors to consider when designing resistance management refuges and field refuge designs

Efficacy and Persistence of \u3ci\u3eSteinernema carpocapsae\u3c/i\u3e (Rhabditida: Steinemematidae) Applied through a Center-Pivot Irrigation System Against Larval Corn Rootworms (Coleoptera: Chrysomelidae)

We evaluated control of natural and artificially infested populations of larval com rootworms (Diabrotica virgifera virgifera LeConte and D. barberi Smith & Lawrence) in corn (Zea mays L.) treated with entomopathogenic nematodes, Steinernema carpocapsae (Weiser); All strain, applied after planting through a center-pivot irrigation system at 2.5 and 1.2 x 109 infective juvenile nematodes per hectare. We compared control achieved with nematodes with that achieved with planting time applications of terbufos (Counter 15G [granular]; 9.9 kg [AI]/ha) and chlorpyrifos (Lorsban 4E [emulsion]; 1.12 kg [AI]/ha) applied after planting through an irrigation system, and with an untreated (water only) control. In 1989 studies with natural rootworm populations, chlorpyrifos and both nematode rates provided significantly lower root damage ratings than terbufos and the untreated control. Chlorpyrifos was significantly more effective than the low nematode rate. In 1990 studies with a natural rootworm infestation, the high nematode rate, terbufos, and chlorpyrifos provided significantly lower root damage ratings than the untreated control. Effectiveness of the low rate of nematodes was not significantly different from that of the untreated control. In both years, all treatments were generally less effective under higher rootworm pressure in artificially infested plots. In 1989, the high rate of nematodes significantly reduced adult western corn rootworm emergence compared with terbufos, the low rate of nematodes, and the untreated control. In 1990, all treatments significantly reduced western corn rootworm adult emergence compared with the untreated control. In 1989, viable nematodes were commonly found 1-3 d after application and at low levels 28 d after application. However, in 1990, no viable nematodes were found \u3e7 d after application

Spin polarization asymmetry at the surface of chromia

We demonstrate boundary spin polarization at the surface of a Cr2O3 single crystal using spin-polarized low-energy electron microscopy (SPLEEM), complementing prior spin polarized photoemission, spin polarized inverse photoemission, and x-ray magnetic circular dichroism photoemission electron microscopy measurements. This work shows that placing a Cr2O3 single crystal into a single domain state will result in net Cr2O3 spin polarization at the boundary, even in the presence of a gold overlayer. There are indications that the SPLEEM contrast for the two polarization states may be different, consistent with scanning tunneling microscopy spectroscopy results obtained from ultrathin films of Cr2O3