Background
What is the pathogen responsible for porcine pleuropneumonia?
What is, Actinobacillus pleuropneumoniae?
it is a bacterial pathogen that causes severe respiratory infections in pigs, leading to lung damage and economic losses
Figure 2) The amino acid sequence of apxIVA contains how many GK dipeptides that could potentially be targets for acylation?
What is, 3?
This method was used to separate the bacterial cells in to different components
What is cell fractionation?
What do most toxins in this category (ApxI, ApxII, ApxIII) need to become active?
What is Acetylation?
Since bacteria often evade traditional antibiotics through efflux pumps and enzyme degradation, ApxIVA-based treatments could offer an alternative approach by targeting this essential bacterial structure
What is the periplasm?
What are RTX toxins?
These toxins, including ApxI, ApxII, ApxIII, and ApxIVA, are secreted by A. pleuropneumoniae and play a role in bacterial virulence.
Figure 4) What type of bacteria were used to detect periplasmic PhoA activity?
What is, E. coli?
The dye binds to this part of the cell to see if the it is dead or alive
What is DNA?
What is ORF1 and what is it's purpose?
ORF1 is a small protein that the bacteria send to their periplasm. Its job is to protect A. pleuropneumoniae from ApxIVA’s toxic effects.
Like colicin M, ApxIVA may inhibit this essential cellular process, making it a potential target for new antibiotics.
What is protein/peptidoglycan synthesis?
How does ApxIVA differ from other Apx toxins in A. pleuropneumoniae?
ApxI, ApxII, and ApxIII can lyse host cells, while ApxIVA does not cause hemolysis or direct cytotoxicity.
Figure 1) What region of apxIVA is different than other apx toxins?
What is, the RTX domain repeats?
The spot-on-lawn assay was used in this paper to test this specific property
What is antimicrobial activity?
What do they think triggers ApxIVA production in real infections?
What is, Something in the blood, similar to FBS?
ApxIVA’s membrane-targeting properties could inspire the development of these short, naturally occurring antimicrobial molecules.
What are antimicrobial peptides (AMPs)
What is ApxIVA
Unlike other Apx toxins, this one is produced only in the presence of host-specific factors, such as those found in serum.
Name the key takeaway from figure 5?
Neither ORF1 nor ApxIVA was detected in cells grown in the presence of different concentrations of BSA
This denatures the proteins causing the to become straight and have a consistent negative charge for the western blot assay
What is SDS?
This term describes bacterial toxins like ApxIVA that selectively kill competitor bacteria in a microbial community.
What is, bacteriocin?
By modifying ApxIVA to recognize specific bacterial surface markers, researchers could create this type of highly selective antibacterial toxin.
What is a receptor-targeted bacterial toxin?
Why is understanding the ApxIVA-ORF1 immun-toxin system important for veterinary medicine?
The study of ApxIVA and ORF1 could lead to new treatments that reduce the need for antibiotics in pig farming.
Figure 3C) What is the significance of this figure?
Ca2+ ions are dispensable for folding of the ApxIVA protein
The ApxIVA protein was broken down by this enzyme in preparation for mass-spectrometry
What is trypsin?
A. pleuropneumoniae uses the ApxIVA-ORF1 system to compete with other bacteria in this part of a pig’s body.
What is, the respiratory tract (lungs and airway mucosa)?
If ApxIVA can be stabilized and modified for medical use, it could provide an alternative to this last-resort antibiotic used against MDR Gram-negative bacteria.
What is colistin?