Bloodworms Glycera dibranchiata are known for their unusual jaws, which are made of protein (∼50% w/w), ionic and mineralized copper (up to 10%), and melanin (∼40% w/w).
Jaws of Glycera dibranchiata are composites of protein, melanin, and both mineral and ionic copper; to date, nanomechanical tests have correlated the ionic copper and melanin with hardness and wear resistance, but the function of protein is uncertain. Wonderly et al. characterize a Gly- and His-rich protein called multi-tasking protein (MTP) and, using recombinant protein, show that it performs six distinct functions critical for jaw formation and performance, namely (1) recruiting 22 equiv of Cu2+, (2) mediating a liquid-liquid phase separation of the MTP-copper complex, (3) catalyzing the oxidation of 3,4-dihydroxyphenylalanine (Dopa) to melanin, (4) templating the interfacial polymerization of melanin, (5) integrating melanin and itself into thin films and fibers, and (6) providing intermolecular cohesion through Cu bridging. MTP achieves all these by assuming unprecedented roles as a building block, organizer, and fabricator — a processing feat of considerable relevance to the autonomous production of other polymer composites, blends, and/or networks. Image credit: Wonderly et al., doi: 10.1016/j.matt.2022.04.001.
Glycera dibranchiata is a marine polychaete that burrows through intertidal benthic mud to a depth of several meters.
The proboscis of each worm is equipped with four jaws that grasp and inject venom into other creatures during hunting and combat.
Because these worms only form their jaws once, they need to be strong and tough enough to last the entirety of the animal’s five-year lifespan.
“These are very disagreeable worms in that they are ill tempered and easily provoked,” said Professor Herbert Waite, a biochemist at the University of California, Santa Barbara.
“When they encounter another worm, they usually fight using their copper jaws as weapons.”
In the study, Professor Waite and his colleagues were able to observe the chemical process that forms Glycera dibranchiata’s jaw-like material from start to finish.
The bloodworm begins with a protein precursor, which recruits copper to concentrate itself into a viscous, protein-rich liquid that is high in copper and phase-separates from water.
The protein then uses the copper to catalyze the conversion of the amino acid derivative DOPA into melanin, a polymer that, combined with protein, gives the jaw mechanical properties that resemble manufactured metals.
Through this process, the worm is able to easily synthesize a material that, if created in a lab, would be a complicated process involving many different apparatuses, solvents, and temperatures.
“We never expected protein with such a simple composition, that is, mostly glycine and histidine, to perform this many functions and unrelated activities,” Professor Waite said.
The authors hope that a better understanding of how Glycera dibranchiata conducts its self-contained processing laboratory could help to streamline parts of production that would benefit industry.
“These materials could be road signs for how to make and engineer better consumer materials,” Professor Waite said.
The study was published in the journal Matter.
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William R. Wonderly et al. A multi-tasking polypeptide from bloodworm jaws: Catalyst, template, and copolymer in film formation. Matter, published online April 25, 2022; doi: 10.1016/j.matt.2022.04.001
Source link: https://www.sci.news/biology/bloodworm-copper-jaws-10743.html
