Departamento de Bioquímica y Biología Molecular I, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain.
Arch Biochem Biophys. 2013 Apr 1;532(1):39-45. doi: 10.1016/j.abb.2013.01.005. Epub 2013 Jan 29.
Actinoporins are water-soluble proteins with the ability to form pores upon insertion into biological membranes. They constitute a family of proteins with high degree of sequence identities but different hemolytic activities, suggesting that minor conformational arrangements result in major functional changes. A good example of this situation is the sea anemone Stichodactyla helianthus which produces two very similar actinoporins, sticholysins I (StnI) and II (StnII), but of very different hemolytic efficiency. Within this idea, given that the high resolution three-dimensional structure of StnII is already known, we have now solved that one corresponding to StnI in order to analyze the influence of particular residues on the conformation and activity of these proteins. In addition, random mutagenesis has been also used to produce five less hemolytic variants of StnI. All these mutations map to functionally relevant regions because they are probably involved in conformational changes associated with pore formation, which take place after membrane binding, and involve long-distance rearrangements of the polypeptide chain of actinoporins.
肌动蛋白孔道蛋白是水溶性蛋白，插入生物膜后能够形成孔道。它们构成了一个具有高度序列同一性但溶血活性不同的蛋白质家族，这表明微小的构象排列会导致功能的重大变化。这种情况的一个很好的例子是海葵 Stichodactyla helianthus，它产生两种非常相似的肌动蛋白孔道蛋白，即 StnI（StnI）和 II（StnII），但溶血效率却非常不同。在这种情况下，鉴于 StnII 的高分辨率三维结构已经已知，我们现在已经解决了 StnI 的结构，以分析特定残基对这些蛋白质构象和活性的影响。此外，还使用随机诱变产生了 StnI 的五个溶血活性降低的突变体。所有这些突变都映射到功能相关的区域，因为它们可能参与与孔形成相关的构象变化，这种变化发生在膜结合之后，涉及肌动蛋白孔道蛋白的多肽链的长距离重排。
