分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-12
Wu, Huiwen
Gong, Weibin
Wang, Jinfeng
Perrett, Sarah
Yao, Xingzhe
Feng, Yingang
Yao, Xingzhe
Feng, Yingang
Wu, Huiwen
Yao, Xingzhe
摘要： Translationally controlled tumor protein (TCTP) is an abundant protein that is highly conserved in eukaryotes. However, its primary function is still not clear. Human TCTP interacts with the metazoan-specific eukaryotic elongation factor 1B delta (eEF1B delta) and inhibits its guanine nucleotide exchange factor (GEF) activity, but the structural mechanism remains unknown. The interaction between TCTP and eEF1B delta was investigated by NMR titration, structure determination, paramagnetic relaxation enhancement, site-directed mutagenesis, isothermal titration calorimetry, and HADDOCK docking. We first demonstrated that the catalytic GEF domain of eEF1B delta is not responsible for binding to TCTP but rather a previously unnoticed central acidic region (CAR) domain in eEF1B delta. The mutagenesis data and the structural model of the TCTP-eEF1B delta CAR domain complex revealed the key binding residues. These residues are highly conserved in eukaryotic TCTPs and in eEF1B GEFs, including the eukaryotically conserved eEF1B delta, implying the interaction may be conserved in all eukaryotes. Interactions were confirmed between TCTP and the eEF1B delta CAR domain for human, fission yeast, and unicellular photosynthetic microalgal proteins, suggesting that involvement in protein translation through the conserved interaction with eEF1B represents a primary function of TCTP.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
摘要： Hsp70 chaperone proteins play crucial roles in the cell. Extensive structural and functional studies have been performed for bacterial and mammalian Hsp70s. Ssa1 from Saccharomyces cerevisiae is a member of the Hsp70 family. In vivo and biochemical studies on Ssa1 have revealed that it regulates prion propagation and the cell cycle. However, no structural data has been obtained for Ssa1 up to now. Here we report the almost complete (96 %) H-1, C-13, N-15 backbone and side chain NMR assignment of the 18.8 kDa Ssa1 substrate binding domain. The construct includes residues 382-554, which corresponds to the entire substrate binding domain and two following alpha-helices in homologous structures. The secondary structure predicted from the assigned chemical shifts is consistent with that of homologous Hsp70 substrate binding domains.
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