Sequence-encoded folding is the foundation of protein structure and is also possible in synthetic chains of artificial chemical composition. In natural proteins, the characteristics of the unfolded state are as important as those of the folded state in determining folding energetics. While much is known about folded structures adopted by artificial protein-like chains, corresponding information about the unfolded states of these molecules is lacking. Here, we report the consequences of altered backbone composition on the structure, stability, and dynamics of the folded and unfolded states of a compact helix-rich protein. Characterization through a combination of biophysical experiments and atomistic simulation reveals effects of backbone modification that depend on both the type of artificial monomers employed and where they are applied in sequence. In general, introducing artificial connectivity in a way that reinforces characteristics of the unfolded state ensemble of the prototype natural protein minimizes the impact of chemical changes on folded stability. These findings have implications in the design of protein mimetics and provide an atomically detailed picture of the unfolded state of a natural protein and artificial analogues under non-denaturing conditions.
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Proteomimetic zinc finger domains with modified metal‐binding β‐turns
The mimicry of protein tertiary folds by chains artificial in backbone chemical composition leads to proteomimetic analogues with potential utility as bioactive agents and as tools, to shed light on biomacromolecule behavior. Notable successes toward such molecules have been achieved; however, as protein structural diversity is vast, design principles must be continually honed as they are applied to new prototype folding patterns. One specific structure where a gap remains in understanding how to effectively generate modified backbone analogues is the metal‐binding β‐turn found in zinc finger domains. The literature precedent suggests several factors that may act in concert, including the artificial moiety used to modify the turn, the sequence in which it is applied, and modifications present elsewhere in the domain. Here, we report efforts to gain insights into these issues and leverage these insights to construct a zinc finger mimetic with backbone modifications throughout its constituent secondary structures. We first conduct a systematic comparison of four turn mimetics in a common host sequence, quantifying relative efficacy for use in a metal‐binding context. We go on to construct a proteomimetic zinc finger domain in which the helix, strands, and turn are simultaneously modified, resulting in a variant with 23% artificial residues, a tertiary fold indistinguishable from the prototype, and a folded stability comparable to the natural backbone on which the variant is based. Collectively, the results reported provide new insights into the effects of backbone modification on the structure and stability of metal‐binding domains and help inform the design of metalloprotein mimetics.
more » « less- NSF-PAR ID:
- 10456596
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Peptide Science
- Volume:
- 112
- Issue:
- 5
- ISSN:
- 2475-8817
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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LINKED ARTICLES This article is part of a themed issue on Structure Guided Pharmacology of Membrane Proteins (BJP 75th Anniversary). To view the other articles in this section visit
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