Project description:The type III secretion system (T3SS) is an important virulence factor of Gram-negative bacteria, including the genus Aeromonas, a group of aquatic bacteria capable of both mutualistic and pathogenic interactions. Aeromonas species are increasingly recognized as opportunistic human pathogens. The type strain A. schubertii ATCC 43700 encodes two distinct T3SSs located in the Aeromonas pathogenicity islands 1 and 2, hereby designated as API1 and API2, respectively. This work investigates the role of API1 and API2 in A. schubertii-induced cytotoxicity and identifies novel type III secretion effectors. HeLa cell infections showed that API1, but not API2, is essential for cellular cytotoxicity resulting in both apoptotic and necrotic cell death. The ΔAPI1 mutant failed to induce cytotoxicity, whereas the wild-type (WT) and ΔAPI2 strains induced comparable cytotoxic effects. Proteomic analysis identified 7 candidate effectors secreted by the API1 injectisome under low-calcium conditions. These included two previously characterized effectors, AopH and AopO of A. salmonicida, and five novel effectors hereby named AopI, AopJ, AopL, AopT, and AopU, whose injection into host cells via API1 was validated using a split luciferase reporter system. Functional analysis revealed distinct roles for these effectors. AopL, homologous to the VopQ effector of Vibrio cholerae, accelerated caspase 3-independent necrosis, while AopI, homologous to ExoY of Pseudomonas aeruginosa, suppressed caspase activation and necrosis, indicating a pro-survival function. These results show the role of API1 injectisome in the cytotoxicity of A. schubertii and expand our understanding of T3SS-mediated host-pathogen interactions in Aeromonas species.
Project description:We sequenced the complete genome of the type strain of Aeromonas schubertii, ATCC 43700. The full genome sequence of A. schubertii ATCC 43700 is 4,356,858 bp, which encodes 3,842 proteins and contains 110 predicted RNA genes.
Project description:In this study the transcriptomes of Acinetobacter baumannii strains ATCC 17978 and 17978hm were compared. Strain 17978hm is a hns knockout derivative of strain ATCC 17978. Strain 17978hm displays a hyper-motile phenotype on semi-solid Mueller-Hinton (MH) media (0.25% agar). ATCC 17978 and 17978hm from an 37C overnight culture were transferred to the centre of the semi-solid MH plate and incubated at 37C for 8 hours. Only 17978hm cells displayed a motile phenotype and covered the complete surface of the plate. These motile 17978hm cells and the non-motile wild-type ATCC 17978 cells were harvested and RNA was isolated. The comparative transcriptome analysis was performed using the FairPlay labeling kit and a custom made Agilent MicroArray with probes designed to coding regions of the ATCC 17978 genome. The data was analyzed using Agilent GeneSpring GX9 and the significance analysis of microarray MS Excel add-on.
Project description:Corynebacterium glutamicum strain ATCC 21831 is a producer of L-arginine that was created by random mutagenesis. It is resistant to the arginine structural analogue canavanine. In order to identify potential bottlenecks in the biosynthetic pathway that leads to this industrially important amino acid, relative metabolite abundances of biosynthetic intermediates were determined in comparison to the type strain ATCC 13032. An extract of U13C-labeled biomass was used as internal standard, to correct for different ionization efficiencies. Metabolites were identified using the ALLocator web platform.