New insights into structural biology may help design more efficient antibodies

In structural biology, some molecules are very rare and can only be captured with their own toolset. That’s exactly how a multicenter research team led by Soak scientists defined how antibodies recognize a compound called phosphohistidine. It is a highly unstable molecule that has been shown to play a central role in certain cancers, such as liver and breast cancer. Neuroblastoma.

These insights not only set researchers for more advanced research on phosphohistidine and its potential role in cancer, but also scientists can manipulate the shape and atomic composition of antibody binding sites in the future. It makes it possible to design more efficient antibodies.The study was published in Minutes of the National Academy of Sciences February 5th.

We are excited to reveal these new antibody structures as the next new principle. antigen Bookbinding. You can now redesign these antibodies and manipulate their properties to make them more efficient. This study may also provide other scientists with phosphohistidine antibodies that are more suitable for their research objectives. “

Tony Hunter, Study SSenior Author, Renato Dulbecco, Professor, Salk Institute for Biological Cancer, American Cancer Society

Amino acids combine in the correct order to form proteins, some of which can undergo chemical transformations to change the activity of proteins, for better or for worse. One such transformation is a process called phosphorylation. A compound called phosphoric acid is added to the amino acid, changing its shape and charge.

Earlier, hunters have shown that phosphorylation of the amino acid tyrosine can accelerate the progression of cancer. This is a discovery that leads to many anti-cancer drugs. Recently, hunters have turned their attention to the phosphorylation of the amino acid histidine, which produces phosphohistidine, and suspect that this process may also be involved in human illness.

Hunter has developed a set of antibodies that can bind to phosphohistidines in proteins and a series of monoclonal antibodies that can recognize these morphologies using chemically stabilized phosphohistidine analogs. The next step was to understand exactly how the antibody could bind to phosphohistidine.

This allows Hunter to work with Ian Wilson, a professor of structural biology at the Scripps Institute and a world-renowned expert in defining antibody structures using protein crystallography, phosphohistidine. I studied the structure of the antibody.

“My longtime colleague Tony and I have been working on this project for the past seven years,” says Wilson. “We have gained new insights into how antibodies evolve to recognize protein-bound phosphates, which is very satisfying.”

To understand how phosphohistidine is recognized, they needed to image the antibodies in their action to bind to phosphohistidine, forming crystals between each antibody bound to the phosphohistidine peptide.

“To understand the molecular interactions between antibodies and phosphohistidines, we needed to scrutinize them,” said Rajasree Kalagiri, postdoctoral fellow and X-ray crystallography expert. .. “Once the antibody formed crystals, we irradiated those crystals with X-rays to obtain a diffraction pattern. Next, we applied a method of converting the diffraction pattern to a three-dimensional electron density map and used it to atomize. Identified. Antibody structure. “

The crystal structure of the two antibodies solved by the team revealed exactly how the different amino acids were arranged and tightly bound around the phosphohistidine. These five structures are more than twice the number of previously reported phosphate-specific antibody structures and provide insight into how the antibody recognizes both phosphate and bound histidine. ..

They also reveal at the structural level how the two antibodies recognize different forms of phosphohistidine, which allows scientists to design improved antibodies in the future.