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The secret weapon of cells: Do you know what fusion peptides are?
Recently, the scientific community has conducted in-depth research on the phenomenon of cell fusion, revealing the subtle mechanism of fusion between cells and between viruses and cells. This biological process not only plays a vital role in cell biology, but is also closely related to several global health crises. So, what exactly are fusion peptides, and how do these mysterious molecules affect our health?
Cell fusion is the process of forming a hybrid cell from two separate cells, in which many complex mechanisms interact with each other.
Mechanism of virus-cell fusion
The process of viral invasion of host cells usually involves the fusion of cell and viral membranes. There are three major steps in this process: dehydration of the polar head, promotion of hemifusion of the stalk, and opening and expansion of the pore between the fusing cells. Taking HIV as an example, the virus infects the host by fusing with the membrane of immune cells.
The role of fusion proteins
These proteins involved in membrane fusion are called fusogens. Their presence allows viral and cellular membranes to overcome barriers to fusion. According to the research, many animal species may evolve these fusion proteins after being infected by viruses, which makes cell-to-cell fusion possible.
Scientists have discovered that fusion proteins play a vital role in both virus-cell fusion and cell-cell fusion.
Types of fusion proteins
Based on the different structures, fusion proteins are divided into four categories:
- Class I Fusion Proteins: These complexes consist of three units whose fusion loops are buried within the interior of the monomers during the fusion process. After fusion, they refold into different structures.
- Class II fusion proteins: These proteins are also composed of three units, but contain multiple β-sheet structures, and their folding changes are often triggered by environmental acidity.
- Class III fusion proteins: These proteins possess both alpha helices and beta sheets, which dissociate and form new trimer structures during the fusion process.
- Class IV fusion proteins: Although not usually involved in traditional virus-cell fusion, they are able to induce cell-cell fusion when expressed on the surface of certain cells.
The process of mammalian cell fusion
In mammalian cell fusion, although the specific process of fusion may vary, it generally includes five stages:
- Programming of fusion competence: This step enables cells to fuse and usually involves membrane modifications.
- Chemotaxis: The attraction of cells to each other in response to specific chemical signals.
- Membrane adhesion: Cells adhere to each other through various mechanisms in preparation for fusion.
- Membrane fusion: This process typically begins with the mixing of the outer lipid layers to form a fusion pore.
- Post-fusion reset: After fusion is complete, the fusion machinery must be disassembled or readjusted to prevent further fusion.
Fusion peptides play an integral role during these stages, helping cells to cooperate or defend when needed.
Fusion as a therapeutic goal
As scientists gain a deeper understanding of fusion mechanisms, they are beginning to explore how to exploit these mechanisms as strategies for antiviral therapy. For example, by blocking the function of the fusion proteins of certain viruses, it may be possible to effectively combat deadly hemorrhagic viruses, which has significant implications for public health.
Looking back on these complex biological mechanisms, do they give you new insights into the wisdom of cells and the operation of life?
