Construction of an organelle-like nanodevice via supramolecular self-assembly for robust biocatalysts

Abstract

BackgroundWhen using the microbial cell factories for green manufacturing, several important issues need to be addressed such as how to maintain the stability of biocatalysts used in the bioprocess and how to improve the synthetic efficiency of the biological system. One strategy widely used during natural evolution is the creation of organelles which can be used for regional control. This kind of compartmentalization strategy has inspired the design of artificial organelle-like nanodevice for synthetic biology and “green chemistry”.ResultsMimicking the natural concept of functional compartments, here we show that the engineered thermostable ketohydroxyglutarate aldolase from Thermotoga maritima could be developed as a general platform for nanoreactor design via supramolecular self-assembly. An industrial biocatalyst-(+)-γ-lactamase was selected as a model catalyst and successful encapsulated in the nanoreactor with high copies. These nanomaterials could easily be synthesized by Escherichia coli by heterologous expression and subsequently self-assembles into the target organelle-like nanoreactors both in vivo and in vitro. By probing their structural characteristics via transmission electronic microscopy and their catalytic activity under diverse conditions, we proved that these nanoreactors could confer a significant benefit to the cargo proteins. The encapsulated protein exhibits significantly improved stability under conditions such as in the presence of organic solvent or proteases, and shows better substrate tolerance than free enzyme.ConclusionsOur biodesign strategy provides new methods to develop new catalytically active protein-nanoreactors and could easily be applied into other biocatalysts. These artificial organelles could have widely application in sustainable catalysis, synthetic biology and could significantly improve the performance of microbial cell factories.Graphical Abstract Electronic supplementary materialThe online version of this article (10.1186/s12934-018-0873-3) contains supplementary material, which is available to authorized users.

Nanoreactor Design Based on Self-Assembling Protein Nanocages

“…Generally, the main benefit in coupling nanomaterials with catalytic reactions is to bring them to an appropriate nanoscale (20–50 nm diameter). They are highly homogeneous, easily prepared, and chemically or genetically functionalized [66,67,71,72,95]. Moreover, the transition of the assembly–depolymerization state of these nanocages can be precisely controlled, which makes them an important class of biological nano-elements that can be used to construct multi-functional nano-structures and devices [49,61,63,64].…”

“…Recent progress on encapsulin and artificial protein nanocages provide more options and are ripe for expansion in the near future [8,38,39,89]. It has been proven that these self-assembled nanomaterials could confer benefits by serving as catalytic reaction vessels to the biocatalyst cargo [49,64,71,75,95]. Despite these achievements, there are still several directions that warrant continued research.…”

“…The encapsulated (+)-γ-lactamase exhibits significantly improved stabilities with respect to heat, organic solvent, and protease degradation. Moreover, it shows better substrate tolerance than the free enzyme [95]. This research demonstrates that bio-designed artificial protein nanocages are an effective way to improve the stability and strength of biocatalysts and might have broader applications in sustainable catalysis and synthetic biology.…”

“…These high-symmetry artificial protein nanomaterials have large interior volumes and are widely applicable in vaccine development and synthetic biology. We have recently demonstrated that the artificial hypersTable 60-subunit protein dodecahedron could be functionalized as a scaffold for nanoreactor construction [95]. The engineered trimeric aldolase from Thermotoga maritima with a modified interface was fused with an industrial biocatalyst (+)-γ-lactamase from Microbacterium hydrocarbonoxydans and the hybridized protein could be self-assembled into an organelle-like nanodevice (Figure 4) [95].…”

“…We have recently demonstrated that the artificial hypersTable 60-subunit protein dodecahedron could be functionalized as a scaffold for nanoreactor construction [95]. The engineered trimeric aldolase from Thermotoga maritima with a modified interface was fused with an industrial biocatalyst (+)-γ-lactamase from Microbacterium hydrocarbonoxydans and the hybridized protein could be self-assembled into an organelle-like nanodevice (Figure 4) [95]. The constructed nanoreactor is readily used for enzymatic resolution of Vince lactam, an important intermediate for synthesis of carbocyclic nucleoside medicines [95,96,97].…”