Metal-directed, chemically tunable assembly of one-, two- and three-dimensional crystalline protein arrays

Abstract

Proteins represent the most sophisticated building blocks available to an organism or the laboratory chemist. Yet, in contrast to nearly all other types of molecular building blocks, the designed self-assembly of proteins has been largely inaccessible owing to the chemical and structural heterogeneity of protein surfaces. To circumvent the challenge of programming extensive non-covalent interactions for controlling protein self-assembly, we had previously exploited the directionality and strength of metal coordination interactions to guide the formation of closed, homoligomeric protein assemblies. Here, we extend this strategy to the generation of periodic protein arrays. We show that a monomeric protein with properly oriented coordination motifs on its surface can arrange upon metal binding into one-dimensional nanotubes, and two-or three-dimensional crystalline arrays whose dimensions collectively span nearly the entire nano- and micrometer length scale. The assembly of these arrays is predictably tuned by external stimuli, such as metal concentration and pH.

Flexible, symmetry-directed approach to assembling protein cages

“…An important realization was that a large number of complex symmetries could be generated from only two distinct symmetry elements (for a protein, these must be rotational symmetries specified by its quaternary structure), provided the orientation of the symmetry axes with respect to each other could be carefully controlled. These principles have now been quite widely applied to design both protein cages and protein networks (16)(17)(18)(19)(20)(21)(22). The principal challenge to researchers has been to design new interactions between the protein subunits that promote assembly in the desired geometry, and, in particular, to align the angle between symmetry axes correctly.…”

“…The principal challenge to researchers has been to design new interactions between the protein subunits that promote assembly in the desired geometry, and, in particular, to align the angle between symmetry axes correctly. A variety of strategies have been used to facilitate assembly; these include genetically linking two protein interaction domains (14,23,24), the use of bifunctional ligands and metal ions to coordinate proteins (19,21,22,25), and the computational design of new protein-protein interfaces (16,17).…”

Protein crystalline frameworks with controllable interpenetration directed by dual supramolecular interactions

“…In fact, these frameworks are very special and attractive for biomimetic and nanotechnological studies as well as for further applications because they could augment the useful functionalities of numerous proteins through dense packing and uniform orientation 9 . X-ray diffraction has been a powerful tool for the study of PCF because it provides the most accurate details of the structure and the packing parameters of protein arrays 10,11 . However, the crystallographic research progress of PCF is, to some extent, restricted because very limited numbers of proteins naturally assemble to form crystalline frameworks and the process of formation of crystalline structures is typically extremely slow.…”

Self-assembling all-enzyme hydrogels for biocatalytic flow processes

“…The ultimately high concentrations of the biocatalytic entities realized in our hydrogels are comparably only to the so-called "cross-linked enzyme aggregates" (CLEA) that can be produced from two or more different proteins in a non-directional fashion by glutaraldehyde mediated unselective cross-linking 40 or by sophisticated exploitation of metal coordination interactions 41 . These approaches, however, have their limitations in terms of insufficient control over enzyme stoichiometry or sensitivity to environmental conditions (e.g., pH and ion-strength of reaction media), respectively.…”