De Novo Proteins with Life-Sustaining Functions Are Structurally Dynamic.

TitleDe Novo Proteins with Life-Sustaining Functions Are Structurally Dynamic.
Publication TypeJournal Article
Year of Publication2016
AuthorsMurphy, GS, Greisman, JB, Hecht, MH
JournalJ Mol Biol
Volume428
Issue2 Pt A
Pagination399-411
Date Published2016 Jan 29
ISSN1089-8638
KeywordsAmino Acid Sequence, Biophysical Phenomena, Chromatography, Gel, Circular Dichroism, Escherichia coli, Magnetic Resonance Spectroscopy, Microbial Viability, Molecular Sequence Data, Protein Conformation, Protein Multimerization, Proteins
Abstract

<p>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 Escherichia 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 suggests that dynamic structures may have been important in the early evolution of protein function. </p>

DOI10.1016/j.jmb.2015.12.008
Alternate JournalJ. Mol. Biol.
PubMed ID26707197
PubMed Central IDPMC4744525
Grant ListF32 GM106622 / GM / NIGMS NIH HHS / United States
1F32GM106622 / GM / NIGMS NIH HHS / United States