Article Mode of action of parasporin-4, a cytocidal protein from Bac...

Article Mode of action of parasporin-4, a cytocidal protein from Bac...

https://link.springer.com/article/10.1007%2Fs00284-018-1479-z

Bacillus thuringiensis is one of the most important microorganisms used against cancer cell lines in latest studies all over the world. This study aims to perform the isolation, molecular identification, and to identify novel B. thuringiensis strains that specifically targeting human cancer cell-killing activities in Iran. A total of 88 B. thuringiensis isolates were recovered from Iran. Upon the treatment of the non-hemolytic crystal proteins by proteinase K, five isolates belonging to three biotypes, thuringiensis, kurstaki and sotto of B. thuringiensis are found to have different cytotoxicity toward HCT-116 and CCRF-CEM cell lines. Digested inclusions of the isolates consisted of one major poly peptide of 34-kDa, as estimated by sodium dodecyl-sulfate polyacrylamide gel electrophoresis. The structure, molecular identification, and functionality of five isolates inclusion proteins have shown to be closely like to parasporin-2 but their size of activated protein is not similar to this parasporin. It is unclear that discovered damaging proteins are parasporin-2. This 34-kD protein exhibited varying degrees of cytocidal activity toward human colon and blood cancer cells and caused cell swelling and the formation of blebs in the surface of the cells or alteration in cytoskeleton. The soil in the humid and temperate climates of Iran is a good reservoir for parasporin producing B. thuringiensis. The isolated B. thuringiensis strains exhibit specific and different cytocidal activities against human colon and blood cancer cells. Parasporin is a novel cytotoxic protein to human cancer cells produced by B. thuringiensis and these toxins appeared to attack an identical target on human cancer cells

Hello Karen, parasporin-4 (PS4) is a cytotoxic protein produced by Bacillus thuringiensis strain A1470. The general mechanism is the formation of pores in the plasmatic membrane, which results in sequential binding and damages the osmotic balance. This is known as the classic mechanism. The d-endotoxin is ingested, the digestive protease is activated, and then the Cry toxin comes into contact with the N-aminopeptidase and cadherin receptors on the surface membrane. Specific molecular affinities between the toxins and certain receptors result in proteolytic cleavage in the Cry molecule which causes structural changes in the chain and forms oligomers that function as ‘‘pre-pores’’. There is also a third connection to the membrane surface: the N-aminopeptidase receptor has a molecular affinity and acts to anchor the pre-pore in the lipid bilayer. Thus, the change in the pore formation affects the integrity of the membrane and there is a consequent loss of function. The osmotic imbalance then leads to cell death. PS4 aggregated into oligomers on the plasma membrane of PS4-susceptible CACO-2 cells, induces cell swelling and nuclear shrinkage, and, the ballooned cells burst within 24 h. Leakage of lactate dehydrogenase and influx of extracellular FITC-dextrans have also been observed in susceptible cells. See the attached documents for details.Article Parasporin-2 requires GPI-anchored proteins for the efficien...

Article Mode of action of parasporin-4, a cytocidal protein from Bac...

Article Mode of action of parasporin-4, a cytocidal protein from Bac...

Hello, thanks for your reply. Pore-forming mechanism already well known a lot of publications here. http://parasporin.fitc.pref.fukuoka.jp/intro.html

During my studies want to introduce some theory. Its established that the dysfunction of Na+/K+-pump is a common consequence of any pathology, including cancer. At the same time, it is also known that among a number of mechanisms involved in cell volume regulation, Na+/K+-pump has a central role in it. This role of pump is due to its two important properties:

a) Na+/K+-pump which generates Na+ gradient on the membrane serves as an energy source for a number of secondary ionic transporters, such as, Na+/Ca2+, Na+/H+, Na+/sugars, amino acids & other osmolytes.

b) Na+/K+-pump, having the highest metabolic energy (ATP) utilizing mechanism, has a great intracellular signaling role in regulation of sorption properties of intracellular structure as well as in generation of water molecules during oxidative glucose processes in cells. Na+/K+-ATPase (working molecules of Na+/K+-pump) has 4 catalytic subunits having different functional activities and sensitivities to cardiac glycoside: α1 (low), α2 (middle), α3 and α4 (high), the latter is identified only in testis. From these isoforms α1 (fully) and α2 (partly) have ion transporting functions, while α3 isoform only performs intracellular signaling function. By previous our study it was shown that dysfunction of α3 isoform-dependent signaling function controlling cell hydration stimulates carcinogenesis: So during any type of cancer pathology we will see high level of cell hydration and higher water content than normal cell.

We also know that the parasporins are forming in Bt cells during sporulation and cell itself goes to stage sporulation if less nutrients and water in media. So the parasporin parasporal proteineous inclusion is the product of condensation so why the parasporins selectively acting on cancer cells.

Dear Karen A. Darbinyan

Pls. find the attached files

Article Structural Insights into Bacillus thuringiensis Cry, Cyt and...

https://www.tandfonline.com/doi/full/10.3109/07388551.2014.960793

Article Parasporins 1 and 2: Their structure and activity

Article Ohba M, Mizuki E, Uemori A.. Parasporin, a new anticancer pr...

http://ar.iiarjournals.org/content/29/1/427.full

https://www.researchgate.net/publication/266264268_Bacillus_thuringiensis_Mechanism_of_action_resistance_and_new_applications_A_review

https://link.springer.com/article/10.1007%2Fs00284-015-0934-3

https://academic.oup.com/jb/article-abstract/137/1/17/873766?redirectedFrom=fulltext

Hoping this will be helpful to your project, good luck

Best regards

Houda Kawas