Difference between revisions of "Part:BBa K4607009"

As a brief contextualization, bovine mastitis is the result of the infection of the bovine mammary glands caused by pathogenic microorganisms, mainly gram-positive and negative bacteria. This disease reduces milk quality production to a great extent and produces painful damage to the bovine. The main treatment for mastitis is the use of diverse antibiotics, therefore the overuse and misuse of them have caused a real problem in the development of multidrug-resistant pathogens [2]. Our team has conducted an extensive investigation to find an alternative treatment for bovine mastitis without risking the environment.

The principle behind our proposal is the use of fused proteins based on efficient bacteriophage endolysins. The function of a bacteriophage is to infect bacteria in order to kill them. Once the bacteria are infected and the virions are mature, they release holins, which are enzymes that create pores in the inner cell membrane. Endolysins now have access to the cell wall, so they can degrade it. Endolysins have lytic activity for the purpose of setting free the phage progeny to continue infecting other cells [3]. Endolysins are composed of two main domains: the N-terminal, which represents the catalytic domain, and the C-terminal, which is a cell wall binding domain, which interacts by binding itself to the bacterium's cell wall, activating the catalytic region, and causing cell wall lysis. However, the average endolysin lifetime is 20 minutes [4] [3].

Endolysins need to interact with the peptidoglycan layer to identify and lyse the bacterial cell wall, however, gram-negative bacterial structure makes the process more complicated. To overcome our drawbacks, we incorporated the CecA as a potential solution. The addition of CecA to the N-terminal of a fusion protein improves its antibacterial activity against gram-negative bacteria; this is possible because of its cationic regions, which facilitate the interaction with gram-negative bacterial lipids. Consequently, the fusion protein is capable of degrading the inner membranes of the bacteria. CecA has been evaluated in gram-negative bacteria as E. coli successfully [1].

is thought that the cationic part of the C-terminal amphipathic helix interacts with anionic phosphate groups of lipd A present in the outer membrane, facilitating initial contact of the endolysin to target bacteria. Then the hydrophobic part of the amphipathic helix may induce the entrance of the endolysin through the membrane [33,34].

References

[1] Jeong, T.-H., Hong, H.-W., Kim, M. S., Song, M., & Myung, H. (2023). Characterization of Three Different Endolysins Effective against Gram-Negative Bacteria. Viruses, 15(3), 679. https://doi.org/10.3390/v15030679 ‌

[2] World Health Organization. (2021, November 17). Antimicrobial resistance. Who.int; World Health Organization: WHO. https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance

[3] Gutiérrez, D., Fernández, L., Rodríguez, A., & García, P. (2018). Are phage lytic proteins the secret weapon to kill Staphylococcus aureus?. MBio, 9(1), 10-1128. https://doi.org/10.1128/mbio.01923-17

[4] Fernández, L., González, S., Campelo, A. B., Martínez, B., Rodríguez, A., & García, P. (2017). Downregulation of Autolysin-Encoding Genes by Phage-Derived Lytic Proteins Inhibits Biofilm Formation in Staphylococcus aureus. Antimicrobial Agents and Chemotherapy, 61(5), e02724-16. https://doi.org/10.1128/AAC.02724-16

[5] Schmelcher, M., Powell, A. M., Becker, S. C., Camp, M. J., & Donovan, D. M. (2012). Chimeric Phage Lysins Act Synergistically with Lysostaphin To Kill Mastitis-Causing Staphylococcus aureus in Murine Mammary Glands. Applied and Environmental Microbiology, 78(7), 2297–2305. https://doi.org/10.1128/aem.07050-11

[6] Heselpoth, R. D., Euler, C. W., Schuch, R., & Fischetti, V. A. (2019). Lysocins: Bioengineered Antimicrobials That Deliver Lysins across the Outer Membrane of Gram-Negative Bacteria. Antimicrobial Agents and Chemotherapy, 63(6). https://doi.org/10.1128/aac.00342-19 ‌

[7] Kim, S., Patel, D. S., Park, S., Slusky, J., Klauda, J. B., Widmalm, G., & Im, W. (2016). Bilayer Properties of Lipid A from Various Gram-Negative Bacteria. Biophysical Journal, 111(8), 1750–1760. https://doi.org/10.1016/j.bpj.2016.09.001

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