RNA结构好火啊，这一期cell好几篇相关的文章。  

On the cover: A virus must achieve a number of functions in its life cycle, often using a compact genome with a limited number of encoded proteins. As a result, many viral proteins are multifunctional. In this issue, Bornholdt, et al. (pp. 763–774) demonstrate that the multiple functions of a single protein can arise from refolding of the protein into different structures. Like a piece of origami paper that can be folded into many different shapes, the VP40 matrix protein of the Ebola virus can be refolded from a dimer structure critical to cellular trafficking into an RNA-binding ring that controls viral transcription in the infected cell or into a linear hexamer that serves as the structural matrix of newly budded virions. Each structure and each function of VP40 are essential to the virus life cycle. Image: Christina Corbaci, The Scripps Research Institut.

Proteins, particularly viral proteins, can be multifunctional, but the mechanisms behind multifunctionality are not fully understood. Here, we illustrate through multiple crystal structures, biochemistry, and cellular microscopy that VP40 rearranges into different structures, each with a distinct function required for the ebolavirus life cycle. A butterfly-shaped VP40 dimer traffics to the cellular membrane. Once there, electrostatic interactions trigger rearrangement of the polypeptide into a linear hexamer. These hexamers construct a multilayered, filamentous matrix structure that is critical for budding and resembles tomograms of authentic virions. A third structure of VP40, formed by a different rearrangement, is not involved in virus assembly but instead uniquely binds RNA to regulate viral transcription inside infected cells. These results provide a functional model for ebolavirus matrix assembly and the other roles of VP40 in the virus life cycle and demonstrate how a single wild-type, unmodified polypeptide can assemble into different structures for different functions.