Rational design of a hexameric protein assembly stabilized by metal chelation

Abstract

Protein-based self-assembled nanostructures hold tremendous promise as smart materials. One strategy to control the assembly of individual protein modules takes advantage of the directionality and high affinity bonding afforded by metal chelation. Here, we describe the use of 2,2'-bipyridine units (Bpy) as side chains to template the assembly of large structures (MW approx. 35 000 Da) in a metal-dependent manner. The structures are trimers of independently folded 3-helix bundles, and are held together by 2 Me(Bpy) complexes. The assemblies are stable to thermal denaturation, and are more than 90% helical at 90°C. Circular dichroism spectroscopy shows that one of the 2 possible (Bpy) enantiomers is favored over the other. Because of the sequence pliability of the starting peptides, these constructs could find use to organize functional groups at controlled positions within a supramolecular assembly.

Protease and DNase Activities of a Very Stable High-Molecular-Mass Multiprotein Complex from Sea Cucumber Eupentacta fraudatrix

“…Many classical proteases [ 23 , 24 , 25 ] and DNases [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ] from different organisms are dependent and independent on divalent metal ions. Divalent metal ions act as cofactors involved in chemical reactions catalyzed by some enzymes [ 17 ]. It is obvious that whole holothurian organisms also contain metal-dependent and -independent proteases, as well as nucleases, and some of them can be incorporated into a stable complex during molecular complex formation.…”

“…It was shown that the sea cucumber complex accumulates various elements, including those contained in very low concentrations in seawater. Some studies have shown that various metal ions can significantly affect the stability of complexes of very different nature, consisting of charged, hydrophobic and hydrophilic molecules [ 15 , 16 ], as well as proteins and nucleic acids [ 17 , 18 , 19 , 20 , 21 ]. The data indicate that metal-dependent interactions are formed, in addition to hydrogen bonds between the complex components [ 14 ].…”

Phosphorogenic and spontaneous formation of tris(bipyridine)ruthenium in peptide scaffolds

“…Metal complexes found in naturally evolved proteins play an important role in the stabilization of the 3D structure and function of proteins. Inspired by these metal complexes, metals and ligands that are not used in naturally evolved proteins have been incorporated into protein and peptide scaffolds to utilize the potency of the formed metal complexes and/or regulate the structure of the scaffolds . For example, Lee et al demonstrated that a copper‐bipyridine complex formed in a DNA binding protein could oxidatively cleave DNA .…”

“…Micklitsch et al reported that a zinc‐responsive β‐hairpin peptide containing iminodiacetic acid can self‐assemble into a fibrillar hydrogel . Alcala‐Torano et al controlled the assembly of bipyridine‐incorporated helix bundles in a metal‐dependent manner . Therefore, exploring strategies for incorporating metal complexes into proteins and peptides can be advantageous in various applications.…”