Bionanotechnology and its Application to Cancer
Co-workers: Jin Huang, Catharina Melzer, Tomohiko Nakamura, Sam Reddington, Christopher Schoene, Gianluca Veggiani
Bionanotechnology involves manipulating and modifying components of living organisms, to generate tools on the 1-100 nanometre scale with desirable activities. Inspired by extraordinary molecular features from the natural world, we are developing new approaches for investigating cellular function and for disease diagnosis.
Circulating tumour cells and engineering antibody technologies
Capturing the circulating tumour cells (CTCs) from blood samples is one of the most promising approaches to enable early diagnosis of cancer. CTC capture is already allowing rapid feedback on how a patient is responding to therapy and how the tumour is evolving. Existing magnetic CTC isolation approaches only capture the cells expressing high levels of tumour marker (EpCAM and HER2). We have shown how improving antibody affinity and cholesterol loading make it possible to recover low-expressing cancer cells. To improve further the isolation of CTCs, we are developing antibody technologies with new protein architectures and modes of target binding. This includes antibodies that form covalent bonds to endogenous protein targets.
A new generation of protein interactions- Superglue from bacteria
We have harnessed a remarkable feature of the pili on the pathogenic bacterium Streptococcus pyogenes. This enabled us to achieve an irreversible covalent bond between genetically-encoded protein and peptide partners. This bond is stable over time, at high temperatures, and against the forces in biological systems (blood flow, cell migration, molecular motors).
Our latest interaction, SpyTag with SpyCatcher, is the strongest protein interaction yet measured and is starting to be applied for diverse areas of basic research and biotechnology. We are extending this family of protein interactions, to create new possibilities for synthetic protein design:
- peptide-peptide ligation with SpyLigase
- protein tentacles for Circulating Tumour Cell capture
- protein dendrimers for detecting anti-cancer immune responses
- cyclised enzymes for robust diagnostic devices.
Nanohubs and the limits of protein-small molecule interaction strength
The interaction of streptavidin with biotin is one of the strongest non-covalent interactions in nature. Streptavidin is a central tool for bridging and purification in biological research, as well as showing success in clinical trials. We were able to make a version of streptavidin with 10-fold slower biotin dissociation. We have been investigating this interaction to understand mechanical strength of protein-ligand interactions, via single-molecule force spectroscopy, X-ray crystallography, and collisions with bacterial motors on DNA. We are also developing the use of streptavidin as an ultra-stable hub for nanoassembly, in particular to understand T cell signal transduction.
- Fierer JO, Veggiani G, Howarth M. SpyLigase peptide-peptide ligation polymerizes affibodies to enhance magnetic cancer cell capture. Proc Natl Acad Sci U S A. 2014 111(13):E1176-81
- Jain J, Veggiani G, Howarth M. (2013) Cholesterol loading and ultrastable protein interactions determine the level of tumor marker required for optimal isolation of cancer cells. Cancer Research 73(7):2310-21
- Zakeri B, Fierer JO, Celik E, Chittock EC, Schwarz-Linek U, Moy VT, Howarth M. (2012) Peptide tag forming a rapid covalent bond to a protein, through engineering a bacterial adhesin. Proc Natl Acad Sci U S A 109(12):E690-7
- Aleksic T, Chitnis M, Perestenko O, Gao S, Thomas P, Turner G, Protheroe A, Howarth M, Macaulay V. (2010) The type I IGF receptor translocates to the nucleus of human tumor cells. Cancer Research 70(16):6412-9
- Chivers CE, Crozat E, Chu C, Moy VT, Sherratt DJ, Howarth M. (2010) A streptavidin variant with slower biotin dissociation and increased mechanostability. Nature Methods 7(5):391-93
Figure 1: Magnetic isolation of cancer cells
Figure 2: Enhancing one of the strongest non-covalent interactions in nature- crystal structure of traptavidin
Figure 3: Surviving a molecular car-crash. An ultra-stable variant of streptavidin (red and blue) survives collision by the motor protein FtsK (yellow and black) moving along biotinylated DNA at 5 kilobases per second
Figure 4: Cartoon of the conversion of an adhesion protein from pathogenic Streptococci into a genetically-encoded peptide tag which binds irreversibly