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Background

When creating a biological machine that efficiently can kill off specific pathogens without disturbing other cells in its environment, an adhesion system could play a vital role. Getting our probiotic to attach to its target, like Yersinia enterocolitica in our case, could give important advantages in target specificity and delivering medicine in a way that ensures it reaches Y. enterocolitica in a concentration as high as possible. The idea is to manipulate Lactobacillus expression of membrane proteins to create a somewhat stable bonding to any of Yersina’s surface structures, preventing the pathogen from even entering the gut wall. This could be done with a DNA construct coding for a membrane protein that either resembles the bonding that Yersinia makes to our cells or one that itself binds to Yersinia.

We studied the ways of infection of Yersinia Enterocolitica and could determine that the main strategies of entering through the gut wall is by using it’s diverse membrane proteins YadA, Invasin and Ail. YadA and Invasin work together to bind to our cell membranes. While YadA binds to collagen on our cells, Invasin structurally resembles fibronectin , that is present in the extracellular matrix, which is recognized by the fibronectin binding membrane protein Integrin alpha-5-beta-1 in our cell mambranes. [1] Yersinia uses our own cell-to-cell binding mechanism to find a target cell and fooling it to get inside by binding to the Integrin and to the collagen outside and in between cells. [2]
At first glance we thought of manipulating our probiotics to also use the same bioorganic systems. That could be done by expressing collagen like proteins by fusing them with an anchor protein that could transport the whole construct to the outer membrane and keep the collagen part attached to the probiotic surface. YadA binds strongly to some parts of collagen which could be expressed individually. [3]

But by experimenting with collagen, and especially putting it on the surface of a bacterial outer membrane that is meant to enter the human body, is an extremely risky procedure. “As anti-bodies would be produced to target the collagen and anchor protein complex this could lead to an auto immune reaction as they would also react on the collagen naturally present in our body” says Lars Hellman, a professor in immunology in Uppsala University. More about Problems with Yersinia adhesion and developing auto immune disease can be read in this text:TEXT link.

Instead we took inspiration from the killing system we are using which secrets a bacteriocin, CFY, which specifically binds to and ruptures the outer cell membrane of Yersinia.[4] The main focus of the adhesion system drastically changed from expressing human like proteins to expressing the bacteriocine fused with the anchor protein. This process is less studied, as the bacteriocin was first discovered and characterized as early as 2012.[5] If the bacteriocin would survive degradation in stomach like environments and later on find Y. enterocolitica, the bacteriocine, while attaching to the membrane, would somewhat fix the probiotic to its target. Even thou this connection would be much weaker than a system with collagen it is safe and still an advantage to the pathogen killer.

System design

hen creating a biological machine that efficiently can kill off specific pathogens without disturbing other cells in its environment, an adhesion system could play a vital role. Getting our probiotic to attach to its target, like Yersinia enterocolitica in our case, could give important advantages in target specificity and delivering medicine in a way that ensures it reaches Y. enterocolitica in a concentration as high as possible. The idea is to manipulate Lactobacillus expression of membrane proteins to create a somewhat stable bonding to any of Yersina’s surface structures, preventing the pathogen from even entering the gut wall. This could be done with a DNA construct coding for a membrane protein that either resembles the bonding that Yersinia makes to our cells or one that itself binds to Yersinia.

We studied the ways of infection of Yersinia Enterocolitica and

Result

hen creating a biological machine that efficiently can kill off specific pathogens without disturbing other cells in its environment, an adhesion system could play a vital role. Getting our probiotic to attach to its target, like Yersinia enterocolitica in our case, could give important advantages in target specificity and delivering medicine in a way that ensures it reaches Y. enterocolitica in a concentration as high as possible. The idea is to manipulate Lactobacillus expression of membrane proteins to create a somewhat stable bonding to any of Yersina’s surface structures, preventing the pathogen from even entering the gut wall. This could be done with a DNA construct coding for a membrane protein that either resembles the bonding that Yersinia makes to our cells or one that itself binds to Yersinia.

We studied the ways of infection of Yersinia Enterocolitica and

• [1] http://edoc.rki.de/oa/articles/reeQGIo7WUhm/PDF/247mpj5mInEcs.pdf
• [2] http://edoc.rki.de/oa/articles/reeQGIo7WUhm/PDF/247mpj5mInEcs.pdf