2gjh
From Proteopedia
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NMR Structure of CFr (C-terminal fragment of computationally designed novel-topology protein Top7)
Overview
We recently used computational protein design to create an extremely, stable, globular protein, Top7, with a sequence and fold not observed, previously in nature. Since Top7 was created in the absence of genetic, selection, it provides a rare opportunity to investigate aspects of the, cellular protein production and surveillance machinery that are subject to, natural selection. Here we show that a portion of the Top7 protein, corresponding to the final 49 C-terminal residues is efficiently, mis-translated and accumulates at high levels in Escherichia coli. We used, circular dichroism, size-exclusion chromatography, small-angle X-ray, scattering, analytical ultra-centrifugation, and NMR spectroscopy to show, that the resulting C-terminal fragment (CFr) protein adopts a compact, extremely stable, homo-dimeric structure. Based on the solution structure, we engineered an even more stable variant of CFr by disulfide-induced, covalent circularisation that should be an excellent platform for design, of novel functions. The accumulation of high levels of CFr exposes the, high error rate of the protein translation machinery. The rarity of, correspondingly stable fragments in natural proteins coupled with the, observation that high quality ribosome binding sites are found to occur, within E. coli protein-coding regions significantly less often than, expected by random chance implies a stringent evolutionary pressure, against protein sub-fragments that can independently fold into stable, structures. The symmetric self-association between two identical, mis-translated CFr sub-domains to generate an extremely stable structure, parallels a mechanism for natural protein-fold evolution by modular, recombination of protein sub-structures.
About this Structure
2GJH is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Mis-translation of a computationally designed protein yields an exceptionally stable homodimer: implications for protein engineering and evolution., Dantas G, Watters AL, Lunde BM, Eletr ZM, Isern NG, Roseman T, Lipfert J, Doniach S, Tompa M, Kuhlman B, Stoddard BL, Varani G, Baker D, J Mol Biol. 2006 Oct 6;362(5):1004-24. Epub 2006 Aug 4. PMID:16949611 [[Category: ]]
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