Scientists have adapted the genetic modification technology CRISPR to identify antibodies in blood samples from patients in an attempt to encourage new grades of medical diagnostics along with a series of other applications.
Karl Barber holding a PICASSO microarray. Image Credit: Schmidt Science Fellows
The technology uses a customizable package of proteins that are linked to a variant of Cas9, which is a protein at the core of CRISPR, that will stick to DNA. However, it will not detach as it would when employed for genetic modification.
When these Cas9-attached proteins are applied to a microchip featuring thousands of unique DNA molecules, individual proteins within the mixture are capable of self-assembling to organize on the chip holding the corresponding DNA sequence.
The researchers have described this technique as “PICASSO” (peptide immobilization by Cas9-mediated self-organization). By introducing a blood sample to the PICASSO microarray, the proteins on the microchip that are recognized by patient antibodies can be identified.
The research team was led by Dr. Stephen Elledge at Harvard Medical School and Brigham and Women’s Hospital, Boston. The study was published on August 13th, 2020.
The paper’s first author, Dr. Karl Barber, is a 2018 Schmidt Science Fellow, with much of the work to build the technology taking place during his Fellowship Research Placement in the laboratory of corresponding author Dr. Elledge.
Dr Barber continued describing PICASSO, “Imagine you want to paint a picture on a canvas, but instead of painting in a normal fashion, you mix all of your paints together, splash it on the canvas, and the perfect picture emerges. With our new technique, you place DNA molecules at defined locations on a surface and each protein from a mixture will then self-assemble to its corresponding DNA sequence, like an automated paint-by-number kit.
Dr Karl Barber, Study First Author and Schmidt Science Fellow, Harvard Medical School
The resulting DNA-templated protein microarrays allow you to quickly identify antibodies in clinical samples that recognize whatever proteins you are interested in,” added Dr. Barber.
The research team has explained that the technology operates to organize thousands of different proteins, stating that it is possible to readily adapt as a broad-spectrum medical diagnostic tool. The study employed a method to detect antibodies adhering to proteins extracted from pathogens, which include SARS-CoV-2, derived from the blood of recovering COVID-19 patients.
In this work, we demonstrated the application of PICASSO for protein studies, creating a tool that we believe could be quickly adapted for medical diagnostics. Our protein self-assembly technique could also be harnessed for the development of new biomaterials and biosensors just by attaching DNA targets to a scaffold and allowing Cas9-linked proteins to bind.
Dr. Karl Barber, Study First Author, and Schmidt Science Fellow
“One of the most exciting aspects of this work is the demonstration of how CRISPR can be applied in an entirely new setting. Previously, CRISPR has been used primarily for gene editing and the detection of DNA or RNA. PICASSO brings the power of CRISPR into a new realm of protein studies, and the molecular self-assembly strategy we show may assist in developing new research and diagnostic tools,” Dr. Stephen Elledge.
“This technology has the potential to be used as a medical diagnostic tool that could, one day, provide doctors with a way to quickly determine the diagnosis and best course of treatment for each individual patient.
Dr. Megan Kenna, Executive Director, Schmidt Science Fellows
“The way that Karl and the research team have brought together fundamental biology with molecular engineering to make this important discovery shows why the interdisciplinarity at the heart of our Fellowship is so critical to advancing science,” concluded Dr. Kenna.
The research was funded by Schmidt Science Fellows, the Jane Coffin Childs Memorial Fund for Medical Research, National Science Foundation, and the Howard Hughes Medical Institute.
Journal Reference:
Barber, K. W., et al. (2021) CRISPR-based peptide library display and programmable microarray self-assembly for rapid quantitative protein binding assays. Molecular Cell. doi.org/10.1016/j.molcel.2021.07.027.