Difference between revisions of "Part:BBa K4990001"

Revision as of 13:37, 12 October 2023

FK-13

TO KNOW ABOUT IT!

Antimicrobial peptides, which are first discovered in the immune systems of insects, are widely found in living organisms. Subsequently, similar peptides have been extracted from bacteria, fungi, amphibians, higher plants, and mammals. These active peptides possess natural immune functions and serve as essential molecular barriers for host defense against invading pathogens, hence referred to as antimicrobial peptides[1-2].

The tissue proteinase inhibitor family is unique to mammals and constitutes a type of antimicrobial peptide.LL37 is derived from one of the tissue proteinase inhibitors, human cationic antimicrobial protein 18 (hCAP18). Among them, LL-37 is the sole antimicrobial peptide found in the human body. It possesses various functions such as antimicrobial, antitoxin, immunomodulatory, and wound healing effects. Additionally, LL-37 holds potential for treating viral diseases and neoplastic conditions. Numerous research teams have investigated the activity of truncated peptides to identify the minimal antimicrobial region of LL-37. The results indicate that the smallest region of LL-37 is within amino acid positions 17 to 29 or 18 to 29[3-4]. This suggests that the C-terminal helix, consisting of 12 or 13 amino acids of LL-37, plays a role in antimicrobial, antiviral, and antitumor activities.

What is it?

This part is the truncated peptide of LL37, representing the minimal functional segment of LL-37. It consists of only 13 AA and exhibits antimicrobial activity.As a basic part,it functions as a warhead, capable of simultaneously killing both bacteria and colorectal cancer cells.

What can it do?

As a basic part,it functions as a warhead, capable of simultaneously killing both bacteria and colorectal cancer cells.Later, building upon it as a foundation, we incorporated domains targeting Fusobacterium nucleatum (Fn) and colorectal cancer (CRC) on its head and tail. This resulted in a dual-targeting cytotoxic peptide, which we call the "Double-Edged Harpoon".

How does it work?

FK-13 exhibits antibacterial effects against both Gram-positive and Gram-negative bacteria. Through electrostatic interactions, the positively charged FK-13 connects with negatively charged bacteria, inserting into bacterial cell membranes and leading to the leakage of their contents, resulting in cell death.

Currently, two hypotheses support the mechanism by which FK-13 disrupts cell membranes: the carpet model, based on FK-13's cationic amino acids interacting with the phospholipid head groups in the cell membrane, which can form a carpet-like structure on the membrane surface, ultimately compromising membrane integrity. Changes in helical structure, charge, and hydrophobicity influence its antibacterial activity. On the other hand, the toroidal pore model suggests that due to membrane surface tension and curvature, FK-13 induces the formation of toroidal pores in bacterial membranes, causing leakage of bacterial contents and leading to bacterial death.

For mammalian cells, whose membranes are mostly neutral, FK-13's interaction with membranes is comparatively weak, and cells are less susceptible to damage. Furthermore, FK-13 can enhance the rigidity of epithelial cell membranes and reduce their permeability, thus minimizing bacterial attacks. Additionally, FK-13 possesses an amphipathic helical structure, which under hydrophobic conditions promotes oligomerization. The potency of the immune response is directly proportional to the α-helical structure of the oligomers. When there are more α-helices present, the antibacterial activity is stronger[5].

We also performed an exhaustive wet experimental characterization

Detection of anticancer activity of LL-37 and it induces cell death mode | a.Absorbance at 450 nm versus time of administration and concentration of administration. b. Heat map of absorbance at 450 nm versus time of administration and concentration of administration. c. Absorbance at 450 nm of 2 hours after FK-13 administration. d. Absorbance at 450 nm of 4 hours after FK-13 administration. e. Absorbance at 450 nm of 6 hours after FK-13 administration. f. Absorbance at 450 nm of 8 hours after FK-13 administration. (The data were analyzed using student’s T-test; *: P<0.05; **: P<0.01; ***: P<0.001).

Reference

［1］de Breij, A., Riool, M., Cordfunke, R. A., Malanovic, N., de Boer, L., Koning, R. I., Ravensbergen, E., Franken, M., van der Heijde, T., Boekema, B. K., Kwakman, P. H. S., Kamp, N., El Ghalbzouri, A., Lohner, K., Zaat, S. A. J., Drijfhout, J. W., & Nibbering, P. H. (2018). The antimicrobial peptide SAAP-148 combats drug-resistant bacteria and biofilms. Science translational medicine, 10(423), eaan4044.

［2］Zhang, M., Liang, W., Gong, W., Yoshimura, T., Chen, K., & Wang, J. M. (2019). The Critical Role of the Antimicrobial Peptide LL-37/ CRAMP in Protection of Colon Microbiota Balance, Mucosal Homeostasis, Anti-Inflammatory Responses, and Resistance to Carcinogenesis. Critical reviews in immunology, 39(2), 83–92.

［3］Fabisiak, A., Murawska, N., & Fichna, J. (2016). LL-37: Cathelicidin-related antimicrobial peptide with pleiotropic activity. Pharmacological reports : PR, 68(4), 802–808.

［4］Chieosilapatham, P., Ikeda, S., Ogawa, H., & Niyonsaba, F. (2018). Tissue-specific Regulation of Innate Immune Responses by Human Cathelicidin LL-37. Current pharmaceutical design, 24(10), 1079–1091.

［5］Wang, X., Junior, J. C. B., Mishra, B., Lushnikova, T., Epand, R. M., & Wang, G. (2017). Arginine-lysine positional swap of the LL-37 peptides reveals evolutional advantages of the native sequence and leads to bacterial probes. Biochimica et biophysica acta. Biomembranes, 1859(8), 1350–1361.

Sequence and Features