Structure, Stability, and Flexibility of Ribosomal Protein L14e from Sulfolobus solfataricus

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• 作者：Stephen P. Edmondson ; Jacquelyn Turri ; Kelley Smith ; Andrew Clark ; John W. Shriver
• 刊名：Biochemistry
• 出版年：2009
• 出版时间：June 23, 2009
• 年：2009
• 卷：48
• 期：24
• 页码：5553-5562
• 全文大小：1066K
• 年卷期：v.48,no.24(June 23, 2009)
• ISSN：1520-4995

文摘

Ribosomal protein L14e is a component of the large ribosomal subunit in both archaea and eukaryotes. We report here a high-resolution NMR solution structure of recombinant L14e and show that the N-terminal 57 residues adopt a classic SH3 fold. The protein contains a tight turn between strands 1 and 2 instead of the typical SH3 RT-loop, indicating that it is unlikely to interact with neighboring ribosomal proteins using the common SH3 site for proline-rich sequences. The remainder of the protein (39 residues) forms a largely extended chain with a short helix which packs onto the surface of the SH3 domain via hydrophobic interactions. It has the potential of adopting an alternative structure to expose a hydrophobic surface for protein−protein interactions in the ribosome without disruption of the SH3 fold. ¹⁵N relaxation data demonstrate that the majority of the C-terminal chain is well-defined on the SH3 surface. The globular protein unfolds reversibly with a T_m of 102.8 °C at pH 7, making it one of the most stable SH3 domain proteins described to date. The structure of L14e is expected to serve as a model for other members of the L14e family, along with members of the COG2163 group, including L6e and L27e. Interestingly, the N-terminal sequence of L14e shows the greatest similarity of any Sulfolobus protein to the reported N-terminal sequence of Sac8b, a DNA-binding protein reported by Grote et al. ((1986) Biochim. Biophys. Acta 873, 405−413). The likelihood that L14e and Sac8b are the same protein is discussed.