Switchable Zinc(II)-Responsive Globular β-Sheet Peptide

Abstract

The natural function of many proteins depends on their ability to switch their conformation driven by environmental changes. In this work, we present a small, monomeric β-sheet peptide that switches between a molten globule and a folded state through Zn­(II) binding. The solvent-exposed hydrophobic core on the β-sheet surface was substituted by a His3-site, whereas the internal hydrophobic core was left intact. Zn­(II) is specifically recognized by the peptide relative to other divalent metal ions, binds in the lower micromolar range, and can be removed and re-added without denaturation of the peptide. In addition, the peptide is fully pH-switchable, has a pK a of about 6, and survives several cycles of acidification and neutralization. In-depth structural characterization of the switch was achieved by concerted application of circular dichroism (CD) and multinuclear NMR spectroscopy. Thus, this study represents a viable approach toward a globular β-sheet Zn­(II) mini-receptor prototype.

Late‐Stage Functionalisation of Peptides on the Solid Phase by an Iodination‐Substitution Approach

“…Previously, we reported an engineered WW domain, WW‐CA, that was able to bind Zn II via a His 3 ‐site on its surface. The binding of Zn II resulted in a significant conformational change from a molten globule to a folded WW domain [26] . Such a change should be detectable by iFRET, as it is strongly distance dependent.…”

“…The binding of Zn II resulted in a significant conformational change from a molten globule to a folded WW domain. [26] Such a change should be detectable by iFRET, as it is strongly distance dependent. However, before starting the synthesis of a WW-CA variant labelled with N3, we examined the labelled hPin1 WW variants P3_N3 to P7_N3 with respect to iFRET efficiency in dependence on the positioning of the coumarin dye.…”

An Engineered β‐Hairpin Peptide Forming Thermostable Complexes with ZnII, NiII, and CuII through a His3 Site

“…We applied this strategy to the triple‐stranded β‐sheet peptide hPin1 WW domain ( T m =59 °C), [19] but instead of thermostability, the resulting peptide, WW−CA, which also contains a His 3 site on its surface, was a weakly folded molten globule in the apo state. After binding to Zn II , folding could be induced, but T m was only 34 °C [20] . This switching between two states upon metal binding, which is in sharp contrast to Tz2H 3 , was then used to develop a FRET‐based Zn II sensor [21]…”

“…After binding to Zn II , folding could be induced, but T m was only 34 °C. [20] This switching between two states upon metal binding, which is in sharp contrast to Tz2H 3 , was then used to develop a FRET-based Zn II sensor. [21] The robustness of the Tz2H 3 À Cu II structure should be emphasised.…”

Studying Peptide-Metal Ion Complex Structures by Solution-State NMR

“…Zinc-binding can cause significant conformational change in peptides [125] and has been shown to induce oligomerization of amyloid beta, a 42 amino acid polypeptide. Amyloid beta is particularly difficult to study structurally because it forms aggregates spontaneously.…”