Molecular Biology

Protein Nanoparticles
Negative staining electron micrograph of protein nanoparticles produced at the PSI (T. Bierig). The image confirms that 24 small subunits have correctly assembled into uniformly sized nanoparticles.

COVID 19 research
in the BIO divison

One of our teams (Dr. R. Benoit) is specialized in the design of protein nanoparticles, using building blocks found in nature (molecular biomimetics). Virus capsids, for example, are naturally occurring protein nanoparticles that exist in a wide variety of shapes and sizes. Many copies of only few types of protein subunits spontaneously assemble to form these viral envelopes. Through recombinant DNA technology, other proteins or peptides can be fused to the subunits, resulting in the display of the attachments on the nanoparticle surface. This technology can be extremely useful for many applications. For example, engineered virus-like particles with optimized stability and epitope exposure can function as improved vaccines. Unlike viruses, the particles do not contain viral genetic material and they are therefore non-infectious. This also makes them ideal tools for the development of novel methods, for example for the specific detection of viruses.

The movie shows a large protein complex consisting of six copies of each of two types of subunits (shown in green and blue). This is one of the proteins we use as a scaffold for the display of multiple copies of a specific protein or peptide at a high local concentration.
Prof. G.V. Shivashankar
Prof. G.V. Shivashankar, Group Leader, Division of Biology and Chemistry (BIO)
(Foto: Mechanobiology Institute, NUS, Singapore/Melanie Lee)

Why Covid-19 hits older people particularly hard

German edition of the interview with Prof. Dr. G.V. Shivashankar (English edition to follow). For further information, please click here.

SARS-CoV-2_ACE-2
Figure 1. Graphical abstract modified from Walls et al. (2020).

SARS-CoV-2/ACE-2 pseudovirus entry blocking assay

The spike glypcoprotein S of SARS-CoV-2 uses the human Angiotensin Converting Enzyme 2 (ACE2) as an entry receptor and recognizes it with a similar affinity to the 2002–2003 SARS-CoV isolates, which suggests it can spread efficiently in humans, in agreement with the numerous SARS-CoV-2 human-to-human transmission events reported to date (Walls et al., 2020).

For further information, please click here.

human_ciliated_bronchial_epithelial_cell
Human ciliated bronchial epithelial cell imaged by cryo X-ray tomography method (unpublished data). Ciliated bronchial epithelial cells are typical host cells which coronavirus infects. We are working on the mechanism of coronavirus targeting these cells by bio-imaging methods. The cells are cultured and prepared by the Ishikawa group at the BIO department and imaged using ptychographic tomography at the cSAXS beamline.

Tomographic studies of CoV-19 cell recognition

The group of Prof. Takashi Ishikawa is specialized in cryo-electron tomography and cryo X-ray tomography of cilia, small hair-like protrusions on the surface of many cell types, with important functions, such as the clearing pathogens from the lung.

For further information, please click here.