Ancient bond holds life together, literally

The rise of multicellular structures in animals may have hinged on a chemical link between sulfur and nitrogen atoms.

In animal tissues and organs, cells lock into a scaffold of collagen proteins that allows the cells to stick together and coordinate activities, such as tissue repair. Sulfur-nitrogen connections called sulfilimine bonds form essential links that keep the protein scaffold together, researchers have now discovered.

In 2009, Billy Hudson of Vanderbilt University in Nashville and colleagues first noted that protein scaffolds in fruit flies have these sulfilimine bonds, but the researchers didn’t know if the bonds were common. In a new study, the researchers probed a variety of animal tissues for the sulfur-nitrogen bond and mined genome sequences for the bond’s blueprints. The researchers found that sulfilimine bonds evolved more than 500 million years ago and are found across the animal kingdom.

In zebrafish, an organism scientists use to study development, sulfilimine bonds are required for organs to form, Hudson’s team reports December 16 in the Proceedings of the National Academy of Sciences.

Hudson and his colleagues suggest that these primordial chemical links may have sparked the assembly of single cells into complex animals.