Nav: Home

In-cell molecular sieve from protein crystal

February 09, 2017

In nature, proteins are assembled into sophisticated and highly ordered structures, which enable them to execute numerous functions supporting different forms of life. The exquisite design of natural proteins prompted scientists to exploit it in synthetic biology to engineer molecules that can self-assemble into nanoparticles with desired structure and that may be used for various purposes such as gas storage, enzyme catalysis, intracellular drug delivery, etc.

Cytoplasmic polyhedrosis viruses (cypoviruses) infecting insects are embedded in protein crystals called polyhedra which shield the virus from damage. The structure of polyhedra crystals (PhCs) suggests that they can serve as robust containers which can incorporate and protect foreign molecules from degradation, ensuring their compositional and functional stability.

Overview of Research Achievement

Extreme stability of polyhedra under harsh conditions is provided by dense packing of polyhedrin monomers in crystals with solvent channels of very low porosity, which, however, limits the incorporation of foreign particles. Research group led by Satoshi Abe and Takafumi Ueno at Tokyo Institute of Technology hypothesized that if a porous framework inside PhCs is extended without compromising crystal stability, PhCs can be used for accumulation and storage of exogenous molecules in living cells. As in natural PhCs, polyhedrin monomers form a trimer, the scientists assumed that if amino acid residues at the contact interface of each trimer are deleted, the porosity of the resulting crystals would be increased. To achieve this goal, they genetically engineered polyhedrin monomers, which were then expressed and self-assembled in Spodoptera frugiperda IPLB-Sf21AE, the larva of an armyworm moth, infected with baculovirus. The mutant PhCs maintained crystal lattice of the wild-type PhC but had significantly extended porosity (Figure) due to the deletion of amino acid residues with the rearrangement of intra- and intermolecular hydrogen bonds. As a result, the engineered crystals could adsorb 2-4 times more exogenous molecules (fluorescent dyes) compared to the wild type PhC, with up to 5,000-fold condensation of the dyes from the 10 uM solution.

As a next step, the scientists examined the performance of the mutant crystals in living insect cells. PhCs showed high stability in the intracellular environment. Most importantly, the mutant crystals could accumulate and retain the dyes in live cells, while the natural crystals could not.

Rationale crystal design used by scientists at Tokyo Institute of Technology provides a powerful tool for structural manipulation of self-assembled protein crystals to obtain porous nanomaterials with regulated adsorption properties. The engineered porous PhCs can be used as protein containers for in vivo crystal structure analysis of the cellular molecules and bioorthogonal chemistry in various types of living cells.

Structural analysis of microcrystals

Since tiny crystals with only a few microns size were obtained, the structure analyses were performed at beamlines BL32XU and BL41XU at SPring-8, a large synchrotron radiation facility which delivers the most powerful synchrotron radiation. The high-resolution structures were rapidly analyzed with the help of an automated data collection system developed in RIKEN.
-end-


Tokyo Institute of Technology

Related Technology Articles:

How technology use affects at-risk adolescents
More use of technology led to increases in attention, behavior and self-regulation problems over time for adolescents already at risk for mental health issues, a new study from Duke University finds.
Hold-up in ventures for technology transfer
The transfer of technology brings ideas closer to commercialization. The transformation happens in several steps, such as invention, innovation, building prototypes, production, market introduction, market expansion, after sales services.
The ultimate green technology
Imagine patterning and visualizing silicon at the atomic level, something which, if done successfully, will revolutionize the quantum and classical computing industry.
New technology detects COPD in minutes
Pioneering research by Professor Paul Lewis of Swansea University's Medical School into one of the most common lung diseases in the UK, Chronic Obstructive Pulmonary Disease, has led to the development of a new technology that can quickly and easily diagnose and monitor the condition.
New technology for powder metallurgy
Tecnalia leads EFFIPRO (Energy EFFIcient PROcess of Engineering Materials) project, which shows a new manufacturing process using powder metallurgy.
More Technology News and Technology Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Teaching For Better Humans
More than test scores or good grades — what do kids need to prepare them for the future? This hour, guest host Manoush Zomorodi and TED speakers explore how to help children grow into better humans, in and out of the classroom. Guests include educators Olympia Della Flora and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#535 Superior
Apologies for the delay getting this week's episode out! A technical glitch slowed us down, but all is once again well. This week, we look at the often troubling intertwining of science and race: its long history, its ability to persist even during periods of disrepute, and the current forms it takes as it resurfaces, leveraging the internet and nationalism to buoy itself. We speak with Angela Saini, independent journalist and author of the new book "Superior: The Return of Race Science", about where race science went and how it's coming back.