TADPOLES
Numerous questions in biology depend on the detection and
quantification of very small numbers of specific molecules
mixed among large numbers of other molecules. For example,
understanding how genetically identical cells behave differently
requires quantification of differences in small amounts of
regulatory proteins. Similarly, early detection of many diseases
from clinical samples will be facilitated by the ability
to detect and quantify low abundance signature molecules. We
have devised a means to covalently link homogenous affinity
proteins and DNA molecules by controlled, site-specific chemistry.
The chemistry is catalyzed by inteins, protein domains that
excise from polypeptides to rejoin the ends forming a mature
protein. The resulting chimeric molecules, termed tadpoles,
are composed of a protein head and a DNA tail. We utilized
the tadpoles, polymerase chain reaction (PCR) and rigorous
statistical methods to detect and quantify non-nucleic acid
molecules with great precision, over a wide dynamic range
and with sensitivity at or near the limits of PCR. We have
successfully applied the tadpole technology to quantify low
abundance proteins involved in the pheromone response system.
We are in the process of testing new methods to deploy tadpole
technology to detect molecules present in very low numbers
in blood (biomarkers) whose presence may signal early stage
cancer and infection by pathogens. If successful, these new
reagents will facilitate early detection of cancer and increase
patient survival. Similarly, for infectious disease,
early detection should allow better treatment.
References
Burbulis, I., Yamaguchi, K., Yu, R. Resnekov, O., and Brent, R. (2007) Quantifiying small numbers of antibodies with a 'near universal' protein-DNA chimera. Nat. Methods, 12:1101-03. [PubMed ]
Burbulis, I. , Yamaguchi, K., Gordon, A., Carlson, R., and Brent, R.
(2005) Using protein-DNA chimeras to detect and count small
numbers of molecules. Nat Methods, 2:31-37. [ PubMed ]
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