Jan 26 2016

Imprimer ce Article

De Novo Proteins with Life-Sustaining Functions are Structurally Dynamic


Murphy GS, Greisman JB, Hecht MH.


J Mol Biol. 2015 Dec 18. pii: S0022-2836(15)00699-3. doi: 10.1016/j.jmb.2015.12.008. [Epub ahead of print]


Designing and producing novel proteins that fold into stable structures and provide essential biological functions are key goals in synthetic biology. In initial steps toward achieving these goals, we constructed a combinatorial library of de novo proteins designed to fold into 4-helix bundles. As described previously, screening this library for sequences that function in vivo to rescue conditionally lethal mutants of E. coli (auxotrophs) yielded several de novo sequences, termed SynRescue proteins, which rescued four different E. coli auxotrophs. In an effort to understand the structural requirements necessary for auxotroph rescue, we investigated the biophysical properties of the SynRescue proteins, using both computational and experimental approaches. Results from circular dichroism, size exclusion chromatography, and NMR demonstrate that the SynRescue proteins are α-helical and relatively stable. Surprisingly, however, they do not form well-ordered structures. Instead, they form dynamic structures that fluctuate between monomeric and dimeric states. These findings show that a well-ordered structure is not a prerequisite for life-sustaining functions, and suggest that dynamic structures may have been important in the early evolution of protein function.

Lien Permanent pour cet article : http://www.bernardoffmann.fr/archives/805