Project description:The Type VI secretion system (T6SS) is a bacterial mechanism that delivers effectors to eliminate competitors and modulate host responses. We previously discovered that the oral symbiont Aggregatibacter aphrophilus uses its T6SS to kill the pathobiont Aggregatibacter actinomycetemcomitans. To understand how the T6SS-dependent mechanism of A. aphrophilus affects host cells and A. actinomycetemcomitans, we co-cultured our immortalised epithelial cell line with A. actinomycetemcomitans and various strains of A. aphrophilus: wild-type (HK83 + JP2, n = 6), a T6SS-deficient strain (HK83 Δhcp + JP2, n = 6), and double mutants (HK83 Δtle5 Δglh + JP2, n = 6). As a baseline, we also examined single inoculations of A. aphrophilus (HK83, n = 6), the Δhcp mutant (HK83 Δhcp, n = 6), the Δtle5 Δglh mutant (HK83 Δtle5 Δglh, n = 6), and A. actinomycetemcomitans JP2 (JP2, n = 6). Cells not challenged served as controls. This study aims to identify specific effectors and characterize host responses to A. aphrophilus T6SS.
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:The Type VI Secretion System (T6SS) in bacteria is a versatile mechanism that facilitates protein transport into neighboring cells and can act as an antibacterial weapon by eliminating competing organisms in the vicinity. The objective of this study was to characterize the T6SS in Aggregatibacter aphrophilus and assess its antimicrobial capabilities through competition with Aggregatibacter actinomycetemcomitans in a multispecies biofilm. The proteomic analysis consisted of two parts, referred to as monospecies biofilm and multispecies biofilms, respectively. Initially, we examined the protein profiles of monospecies biofilms formed by two strains of Aggregatibacter aphrophilus, namely HK83 and CCUG 11575, along with their Hcp mutant derivatives (Hcp being a core protein for T6SS). Each strain was analyzed with six replicates (n=4 for HK83, HK83 hcp, CCUG 11575, and CCUG 11575 hcp). Subsequently, the HK83 and CCUG 11575 strains, as well as their Hcp mutant derivatives, were individually introduced into a multispecies biofilm. This multispecies biofilm consisted of seven species, namely A. actinomycetemcomitans JP2 strain (OMZ 295), Actinomyces oris (OMZ 745), Candida albicans (OMZ 110), Fusobacterium nucleatum subsp. nucleatum KP-F2 (OMZ 598), Streptococcus oralis SK248 (OMZ 607), Streptococcus mutans UA159 (OMZ 918), and Veillonella dispar ATCC 17748T (OMZ 493). These species were selected to mimic the natural co-habitat of A. aphrophilus and A. actinomycetemcomitans. Furthermore, control 7-species biofilms with A. aphrophilus strains HK83, HK83 hcp, CCUG 11575, and CCUG 11575 hcp (n=4 each) underwent proteomic analysis to gain insights into the protein expression and potential interactions within the biofilm community.