Solution Structure of C-Terminal Escherichia coli Translation Initiation Factor IF2 by Small-Angle X-ray Scattering
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- 作者：Louise Carø ; e Vohlander Rasmussen ; Cristiano Luis Pinto Oliveira ; Janni Mosgaard Jensen ; Jan Skov Pedersen ; Hans Uffe Sperling-Petersen ; Kim Kusk Mortensen
- 刊名：Biochemistry
- 出版年：2008
- 出版时间：May 20, 2008
- 年：2008
- 卷：47
- 期：20
- 页码：5590 - 5598
- 全文大小：6950K
- 年卷期：v.47,no.20(May 20, 2008)
- ISSN：1520-4995
文摘
Initiation of protein synthesis in bacteria involves the combined action of three translation initiation factors, including translation initiation factor IF2. Structural knowledge of this bacterial protein is scarce. A fragment consisting of the four C-terminal domains of IF2 from Escherichia coli was expressed, purified, and characterized by small-angle X-ray scattering (SAXS), and from the SAXS data, a radius of gyration of 43 
1 Å and a maximum dimension of ~145 Å were obtained for the molecule. Furthermore, the SAXS data revealed that E. coli IF2 in solution adopts a structure that is significantly different from the crystal structure of orthologous aIF5B from Methanobacterium thermoautotrophicum. This crystal structure constitutes the only atomic resolution structural knowledge of the full-length factor. Computer programs were applied to the SAXS data to provide an initial structural model for IF2 in solution. The low-resolution nature of SAXS prevents the elucidation of a complete and detailed structure, but the resulting model for C-terminal E. coli IF2 indicates important structural differences between the aIF5B crystal structure and IF2 in solution. The chalice-like structure with a highly exposed α-helical stretch observed for the aIF5B crystal structure was not found in the structural model of IF2 in solution, in which domain VI-2 is moved closer to the rest of the protein.
1 Å and a maximum dimension of ~145 Å were obtained for the molecule. Furthermore, the SAXS data revealed that E. coli IF2 in solution adopts a structure that is significantly different from the crystal structure of orthologous aIF5B from Methanobacterium thermoautotrophicum. This crystal structure constitutes the only atomic resolution structural knowledge of the full-length factor. Computer programs were applied to the SAXS data to provide an initial structural model for IF2 in solution. The low-resolution nature of SAXS prevents the elucidation of a complete and detailed structure, but the resulting model for C-terminal E. coli IF2 indicates important structural differences between the aIF5B crystal structure and IF2 in solution. The chalice-like structure with a highly exposed α-helical stretch observed for the aIF5B crystal structure was not found in the structural model of IF2 in solution, in which domain VI-2 is moved closer to the rest of the protein.