Scientists identify structure of protein involved in magnetoreception

Published: November 20, 2015

THE EARTH’S magnetic field is used by a variety of animal species to guide large population actions such as migration. Identifying the structure of this protein pushes the field forward to understand just how animals use the earth’s magnetic field for navigation.

PHOTO COURTESY OF WIKIMEDIA COMMONS / THE EARTH’S magnetic field is used by a variety of animal species to guide large population actions such as migration. Identifying the structure of this protein pushes the field forward to understand just how animals use the earth’s magnetic field for navigation.

MATTHEW REYNOLDS
Staff Writer

Researchers from China have identified an elusive protein complex involved in magnetoreception, the ability to sense the Earth’s magnetic field. Animals have been known to possess this ability to sense the Earth’s magnetic field (known as magnetosensing) for some time. For example, Monarch butterflies use the Earth’s magnetic fields to migrate south for the winter. However, the scientific community’s understanding of the way in which these animals are able to sense these fields was largely unclear. To address this issue, the team primarily worked with a Drosophila fly model.

The research group, led by head authors Siying Qin and Hang Yin from the School of Life Sciences in Peking University, Beijing, China, focused on two proteins: Cry and MagR. Cry is a protein known as cryptochrome that has long been thought to be involved in magnetoreception. However, Cry cannot work alone, so the group sought to identify a putative protein, MagR, thought to contain iron or iron-sulfur clusters for ferromagnetic properties.

The team’s approach to solving the magnetoreception question follows a recent trend in biology: answering basic biological questions often requires collaborative efforts between disciplines.

In the paper’s introduction, the authors stated that they identified “a putative magnetic receptor (MagR) and a multimuric magnetosensing rod-like protein complex” using “theoretical postulation and genome-wide screening and validated with cellular, biochemical, structural and biophysical methods.”

Essentially, the authors of the paper developed a theoretical framework that used bioinformatics and computational biology techniques to narrow the search for their proteins of interest by initially screening for iron-binding proteins in the head of fruit flies. The group then refined its search through a careful review of the literature.

Finally, experimentation with the molecular biology techniques of tandem co-purification and polymerase chain reaction with reverse transcription narrowed the potential proteins to a single protein, MagR. This MagR protein, which allows for binding of iron clusters, is expressed in the brain and can form a larger protein complex with another candidate for magnetoreception.

After using primarily computational and molecular biological approaches to identify the protein, the team then turned to biochemical techniques such as size exclusion chromatographic separation to isolate the protein. This isolated protein was then structurally characterized using negative staining transmission electron microscopy. Finally, molecular modeling, the computer-based technique for representing three-dimensional chemical structures at angstrom resolution, bridged the structural work with the theoretical biocompass model.

The team continued with its work and used a technique common in histology to confirm its findings at an organismal level. Confocal microscopy analysis of tissues stained with fluorescent antibodies specific to their target proteins confirmed co-localization of the MagR and Cry proteins in the retina of pigeons.

The work both advances the scientific community’s understanding of magnetoreception and underscores the importance of collaborative efforts between disciplines to answer questions appealing to both. The group of nineteen co-authors affiliated with six institutions published its findings in “Nature, Materials.”

Contact the writer: matthew.reynolds2@scranton.edu

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