Detection and discrimination of Shigella sonnei and Shigella flexneri based on vacuolar responses in Saccharomyces cerevisiae

Targeted Killing of Staphylococcus aureus Using Specific Peptides Displayed on Yeast Vacuoles

Staphylococcus aureus is a common pathogen that causes health care-related and community-associated infections. In this study, we provide a novel system that can recognize and kill S. aureus bacteria. The system is specifically based on a combination of the phage display library technique and yeast vacuoles. A phage clone displaying a peptide capable of specific binding to a whole S. aureus cell was selected from a 12-mer phage peptide library. The peptide sequence was SVPLNSWSIFPR. The selected phage's ability to bind specifically with S. aureus was confirmed using an enzyme-linked immunosorbent assay, and the chosen peptide was then synthesized. The results showed that the synthesized peptides displayed high affinity with S. aureus but low binding ability with other strains, including Gram-negative and Gram-positive bacteria such as Salmonella sp., Shigella spp., Escherichia coli, and Corynebacterium glutamicum. In addition, yeast vacuoles were used as a drug carrier by encapsulating daptomycin, a lipopeptide antibiotic used to treat Gram-positive bacterial infections. The expression of specific peptides at the encapsulated vacuole membrane created an efficient system that can specifically recognize and kill S. aureus bacteria. IMPORTANCE The phage display method was used to select peptides with high affinity and specificity for S. aureus, and these peptides were then induced to be expressed on the surface of yeast vacuoles. These surface-modified vacuoles can act as drug carriers, with drugs such as the lipopeptide antibiotic daptomycin loaded inside. An advantage of using yeast vacuoles as a drug carrier is that they can be easily produced through yeast culture, making the approach cost-effective and suitable for large-scale production and potential implementation in clinical settings. This novel approach offers a promising way to specifically target and eliminate S. aureus that could ultimately lead to improved treatment of bacterial infections and reduced risk of antibiotic resistance.

Melanin Treatment Effect of Vacuoles-Zinc Oxide Nanoparticles Combined with Ascorbic Acid

Currently, ascorbic acid (AA) is widely used as a skin whitening material, but, AA, an unstable hydrophilic molecule, cannot penetrate the skin easily, due to the hydrophobic character of the stratum corneum. Therefore, we conjugated AA with hydrated zinc oxide-an inorganic matrix with positive surface charge, to improve the stability of AA. The metal-conjugated-ascorbic acid (ZnAA) was then combined with yeast vacuole through the vacuolar membrane proteins that relate to metal transportation to create an enhanced vacuole that contained ZnAA. The characteristics of vacuole with ZnAA (ZnAA_Vac) were next examined by various tests that included X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray (EDX) analysis. Furthermore, the ability of ZnAA_Vac to degrade melanin was confirmed in both melanoma cell line B16F10, and the artificial human skin MelanoDerm. The results showed that ZnAA_Vac possessed a higher depigmenting effect than the wild-type vacuole or ascorbic acid by reducing 75% of melanin color. Interestingly, ZnAA_Vac was found to be harmless, and did not cause any cytotoxicity to the cells. Overall, ZnAA_Vac is expected to provide a robust, harmless, and effective whitening agent for the skin.

Intracellular protein delivery using QRPL - A vacuolar targeting signal on carboxypeptidase Y

The signal peptide sequence is known to increase transport efficiency to organelles in eukaryotic cells. In this study, we focus on the signal peptide of the vacuolar protein for vacuolar targeting. The signal peptide sequence QRPL of carboxypeptidase Y (CPY) was inserted inside the interest protein that does not locate in the vacuole for vacuolar targeting. We constructed recombinant strains MBTL-Q-DJ1 and MBTL-Q-DJ2 containing QRPL and green florescent protein (GFP) or aldehyde dehydrogenase 6 (ALD6), respectively. The protein location was then confirmed by confocal microscopy. Fascinatingly, the green fluorescent protein that contains QRPL inside the sequence could be expressed faster than its natural form (within 1 h after induction). Also, the aldehyde removal activity of ALD6 protein in the recombinant yeast was then analyzed by measuring the luminescent intensity in Vibrio fischeri. We confirmed that MBTL-Q-DJ2 containing ALD6 protein has the aldehydes-reducing ability, and in particular, the highest efficiency showed at 500 μg/μL of vacuolar enzyme. In summary, the signal peptide QRPL could be used not only to transport proteins accurately to vacuole but also to improve the protein activity and shorten the induction time.

Cell blocking: An enhancement of foodborne pathogen detection by fluorescent signals of recombinant yeasts

Cell blocking (CB) technique has been widely applied in many studies since the last century. In our research, this technique was mostly used to study the enhancement of the vacuolar response-based system that could detect Shigella sp. and Salmonella sp. investigated in previous studies. The recombinant yeast cells were blocked by mixing with agarose gel on a 96-wells plate, then storing this plate in -80 °C before using. The optimal conditions for the new system, such as agarose concentration, maximum storage time, were also established. Finally, the efficiency of the vacuolar response-based system was improved, and this system could be used as a portable detector for the foodborne pathogen.