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•Recognition of functional amyloid structures with diverse biological activities is growing.•The polymeric β‑sheet rich amyloid architecture accommodates different sequences, but ...individual amyloids display selectivity.•Functional amyloids require precise control over assembly and disassembly.•Activity controlled by conformational change, proteolytic generation of amyloidogenic fragments, heteromeric seeding and supramolecular assembly.•Understanding of the evolved mechanisms that regulate functional amyloid structures can inspire the development of novel amyloid-based biomaterials.
Functional amyloids are a rapidly expanding class of fibrillar protein structures, with a core cross-β scaffold, where novel and advantageous biological function is generated by the assembly of the amyloid. The growing number of amyloid structures determined at high resolution reveal how this supramolecular template both accommodates a wide variety of amino acid sequences and also imposes selectivity on the assembly process. The amyloid fibril can no longer be considered a generic aggregate, even when associated with disease and loss of function. In functional amyloids the polymeric β-sheet rich structure provides multiple different examples of unique control mechanisms and structures that are finely tuned to deliver assembly or disassembly in response to physiological or environmental cues. Here we review the range of mechanisms at play in natural, functional amyloids, where tight control of amyloidogenicity is achieved by environmental triggers of conformational change, proteolytic generation of amyloidogenic fragments, or heteromeric seeding and amyloid fibril stability. In the amyloid fibril form, activity can be regulated by pH, ligand binding and higher order protofilament or fibril architectures that impact the arrangement of associated domains and amyloid stability. The growing understanding of the molecular basis for the control of structure and functionality delivered by natural amyloids in nearly all life forms should inform the development of therapies for amyloid-associated diseases and guide the design of innovative biomaterials.
The identification of toxic Aβ species and/or the process of their formation is crucial for understanding the mechanism(s) of Aβ neurotoxicity in Alzheimer disease and also for the development of ...effective diagnostic and therapeutic interventions. To elucidate the structural basis of Aβ toxicity, we developed different procedures to isolate Aβ species of defined size and morphology distribution, and we investigated their toxicity in different cell lines and primary neurons. We observed that crude Aβ42 preparations, containing a monomeric and heterogeneous mixture of Aβ42 oligomers, were more toxic than purified monomeric, protofibrillar fractions, or fibrils. The toxicity of protofibrils was directly linked to their interactions with monomeric Aβ42 and strongly dependent on their ability to convert into amyloid fibrils. Subfractionation of protofibrils diminished their fibrillization and toxicity, whereas reintroduction of monomeric Aβ42 into purified protofibril fractions restored amyloid formation and enhanced their toxicity. Selective removal of monomeric Aβ42 from these preparations, using insulin-degrading enzyme, reversed the toxicity of Aβ42 protofibrils. Together, our findings demonstrate that Aβ42 toxicity is not linked to specific prefibrillar aggregate(s) but rather to the ability of these species to grow and undergo fibril formation, which depends on the presence of monomeric Aβ42. These findings contribute significantly to the understanding of amyloid formation and toxicity in Alzheimer disease, provide novel insight into mechanisms of Aβ protofibril toxicity, and important implications for designing anti-amyloid therapies.
Protein therapy has the potential to revolutionize medicine, but the delivery of multiple proteins is challenging because it requires the development of a strategy that enables different proteins to ...be combined together and transported not only into cells, but also to the desired cell compartments, such as the nucleus. Here, an efficient intranuclear protein delivery nanoplatform based on modified ribonuclease A (RNase A) tuned self‐assembly is presented. RNase A bioreversibly modified with adamantane is functionalized with wind chime‐like lysine modified cyclodextrin (WLC) to generate RNase A‐WLC (R‐WLC). R‐WLC can not only enhance the cellular uptake of RNase A and accumulate it into the nucleus, but also works as nanovehicles to efficiently transport deoxyribonuclease I (DNase I) into the nucleus, resulting in greatly improved antitumor efficacy in vitro and in vivo. This protein co‐assembly strategy can be applied to other functional proteins and has great prospects in the treatment of many diseases.
Highly efficient nucleus‐targeted delivery of multi‐protein self‐assembly nanoplatform for combined anticancer therapy has been prepared. The assembled nanoproteins with high protein loading efficiency and endosomal escape ability show enhanced cellular uptake and accumulation in the nucleus, resulting in greatly improved anti‐tumor efficacy of RNase A and DNase I both in vitro and in vivo.
Peptides and proteins have evolved to self‐assemble into supramolecular entities through a set of non‐covalent interactions. Such structures and materials provide the functional basis of life. ...Crucially, biomolecular assembly processes can be highly sensitive to and modulated by environmental conditions, including temperature, light, ionic strength and pH, providing the inspiration for the development of new classes of responsive functional materials based on peptide building blocks. Here, it is shown that the stimuli‐responsive assembly of amyloidogenic peptide can be used as the basis of environmentally responsive microcapsules which exhibit release characteristics triggered by a change in pH. The microcapsules are biocompatible and biodegradable and may act as vehicles for controlled release of a wide range of biomolecules. Cryo‐SEM images reveal the formation of a fibrillar network of the capsule interior with discrete compartments in which cargo molecules can be stored. In addition, the reversible formation of these microcapsules by modulating the solution pH is investigated and their potential application for the controlled release of encapsulated cargo molecules, including antibodies, is shown. These results suggest that the approach described here represents a promising venue for generating pH‐responsive functional peptide‐based materials for a wide range of potential applications for molecular encapsulation, storage, and release.
The study represents a promising venue for generating pH‐responsive functional peptide‐based materials, which are biodegradable and biocompatible, for a wide range of potential applications. The authors have utilized a stimuli‐responsive assembly of amyloidogenic peptide building blocks as the basis of environmentally responsive microcapsules which exhibit release characteristics triggered by a change in pH.
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•Protein self-assembly and their importance in developing artificial metalloenzyme compared to monomeric counterpart.•Catalytic activities by various artificial metalloenzymes based ...on protein assembly.•Recent development of metalloprotein assembly design and construction.
Metalloenzymes play essential roles in biology, whereas artificial metalloenzymes use synthetic metal cofactors for promoting non-natural reactions. In the past decades, tremendous advances have been made in manipulating artificial metalloenzymes for various organic transformation reactions, including C–H activation, C–C coupling, transfer hydrogenation, etc. Advanced methods like “Directed evolution,” “high throughput screening,” and “rational design” have stimulated the artificial metalloenzyme research. Applications of artificial metalloenzymes have been extended to cells for controlling functions like prodrug activation. Usually, for more complicated processes like multistep reactions or isolation of reaction environments, nature uses sophisticated strategies, such as positional assembly and compartmentalization of catalysts. However, artificial metalloenzyme research in this direction is relatively less. Several researchers have designed and constructed various protein assembly structures through metal coordination. However, only a few of them have been tested for catalytic activities. Assembled metalloenzymes have multiple advantages like promoting multistep reactions, stabilizing the catalyst, cooperativity in the reaction, higher-order complexity, sophisticated structures, confinement of reaction, etc. Therefore, systematic investigations on their design, structure, and activity are necessary to represent them as next-generation biocatalysts. In this context, the current review highlights the importance of self-assembled metalloenzymes, available design strategies, current developments, catalytic activities, and the future direction of the research.
Composites of Proteins and 2D Nanomaterials Demirel, Melik C.; Vural, Mert; Terrones, Mauricio
Advanced functional materials,
July 4, 2018, Letnik:
28, Številka:
27
Journal Article
Recenzirano
Odprti dostop
Recent advances in the nanotechnology of 2D materials, combined with parallel improvements in biotechnology and synthetic biology, have demonstrated that novel and more complex composite materials ...with desired engineered properties and optimized performance can be achieved. The expanding family of 2D crystals fosters research efforts on nonequilibrium materials such as nanostructured composites and complex heterostructures. In particular, controlled assembly of 2D crystals with biomolecules to form composites attracts special interest since it enables precise control over the physical properties of the resulting material. To facilitate the fabrication of these novel bio‐inorganic composite materials by design, it is crucial to understand and control molecular interactions between 2D crystals and the complementary bio‐system. In particular, protein‐based materials with the ability to initiate multiple physical or chemical interactions with 2D crystals prove to be a suitable match for constructing functional bio‐inorganic composites with programmable properties using molecular biology tools. In this review, a detailed survey on emerging nanostructured composites of 2D materials and proteins is presented, and a comprehensive analysis regarding their interactions is provided. Recent and potential applications along with future directions of research regarding the merge of synthetic biology with 2D systems are also discussed.
2D crystals and proteins can establish hybrid material systems with novel properties and higher level of structural complexity. Recent studies highlight rational combinations of 2D materials and natural/synthetic proteins, which offer structures and properties beyond the individual counterparts.
Nature's optimization of protein functions is a highly intricate evolutionary process. In addition to optimal tertiary folding, the intramolecular recognition among the monomers that generate ...higher‐order quaternary arrangements is driven by stabilizing interactions that have a pivotal role for ideal activity. Homotetrameric avidin and streptavidin are regularly utilized in many applications, whereby their ultra‐high affinity toward biotin is dependent on their quaternary arrangements. In recent years, a new subfamily of avidins was discovered that comprises homodimers rather than tetramers, in which the high affinity toward biotin is maintained. Intriguingly, several of the respective dimers have been shown to assemble into higher‐order cylindrical hexamers or octamers that dissociate into dimers upon biotin binding. Here, we present wilavidin, a newly discovered member of the dimeric subfamily, forming hexamers in the apo form, which are uniquely maintained upon biotin binding with six high‐affinity binding sites. Removal of the short C‐terminal segment of wilavidin resulted in the presence of the dimer only, thus emphasizing the role of this segment in stabilizing the hexamer. Utilization of a hexavalent biotin‐binding form of avidin would be beneficial for expanding the biotechnological toolbox. Additionally, this unique family of dimeric avidins and their propensity to oligomerize to hexamers or octamers can serve as a basis for protein oligomerization and intermonomeric recognition as well as cumulative interactions that determine molecular assemblies.
In this study, we present wilavidin, a novel member of the avidin family forming stable biotin‐binding hexamers. These unique hexamers do not dissociate upon biotin binding, in contrast to all previously reported members of the dimer–multimer subfamily of avidins. Wilavidin provides a starting point for future biotechnological developments requiring high biotin‐binding valency at high affinity, combined with a very good model to study intricate molecular features promoting multimerization.
Silk fibroin is a natural protein obtained from the Bombyx mori silkworm. In addition to being the key structural component in silkworm cocoons, it also has the propensity to self‐assemble in vitro ...into hierarchical structures with desirable properties such as high levels of mechanical strength and robustness. Furthermore, it is an appealing biopolymer due to its biocompatability, low immunogenicity, and lack of toxicity, making it a prime candidate for biomedical material applications. Here, it is demonstrated that nanofibrils formed by reconstituted silk fibroin can be engineered into supramolecular microgels using a soft lithography‐based microfluidic approach. Building on these results, a potential application for these protein microgels to encapsulate and release small molecules in a controlled manner is illustrated. Taken together, these results suggest that the tailored self‐assembly of biocompatible and biodegradable silk nanofibrils can be used to generate functional micromaterials for a range of potential applications in the biomedical and pharmaceutical fields.
Reconstituted silk fibroin nanofibrils are used to generate supramolecular microgels by a soft‐lithography‐based microfluidic approach. The kinetic process of microgel formation has been explored in detail and has been applied to encapsulate small molecules within these microgels. The molecular release‐kinetics for drug‐delivery applications are further evaluated, and it is shown that they are dependent on microgel morphology.
Hydrophobins are surface active proteins produced by filamentous fungi. They have a role in fungal growth as structural components and in the interaction of fungi with their environment. They have, ...for example, been found to be important for aerial growth, and for the attachment of fungi to solid supports. Hydrophobins also render fungal structures, such as spores, hydrophobic. The biophysical properties of the isolated proteins are remarkable, such as strong adhesion, high surface activity and the formation of various self-assembled structures. The first high resolution three dimensional structure of a hydrophobin, HFBII from
Trichoderma reesei, was recently solved. In this review, the properties of hydrophobins are analyzed in light of these new data. Various application possibilities are also discussed.
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•The strategies for constructing self-assembled proteins architectures.•Developing bioinspired materials based on protein assemblies.•Protein assemblies based artificial light ...harvesting systems, intelligent protein nanocarriers, and biomimetic systems.
Sophisticated protein self-assemblies have attracted great scientific interests in recent few decades due to their various potential applications in substance/signal transmission, biosensors, or disease diagnosis and treatment. The design and construction of proteins into hierarchical nanostructures via self-assembly strategies offer unique advantages in understanding the mechanism of naturally occurring protein assemblies and/or creating various functional biomaterials with advanced properties. This review covers the recent progress and trends in the self-assembled hierarchical protein structures and their bio-inspired applications. We initially discuss the design and development of sophisticated protein nanostructures through the preciously designed protein–protein interactions. Many intricate protein nanostructures from quasi-zero dimensional (0D) polyhedral cages, one-dimensional (1D) strings/rings/tubules, two-dimensional (2D) crystal sheets/cambered surfaces, and three-dimensional (3D) crystalline frameworks/hydrogels, have been constructed through self-assembly of rationally designed proteins. In addition, we also show the representative achievements in the study of the structure–function relationship for selected protein self-assemblies and highlight the latest research progress in developing artificial light harvesting systems, biological nanoenzyme mimics, intelligent protein nanocarriers, biomimetic protocells, and so on. As expected, protein self-assembly has become a powerful tool for development of multifarious bioinspired materials with advanced structures and properties.
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