Featured Research

from universities, journals, and other organizations

Wonder Thread: UD Scientists Report First Protein With Collagen And Elastin-Like Domains

Date:
September 23, 1997
Source:
University Of Delaware
Summary:
Five times tougher and 16 times more extensible than a human tendon, the leathery, yet amazingly stretchy collagen threads produced by marine mussels might someday suggest strategies for developing better artificial skin and other biomimetic materials, say University of Delaware researchers.

Five times tougher and 16 times more extensible than a human tendon, the leathery, yet amazingly stretchy collagen threads produced by marine mussels might someday suggest strategies for developing better artificial skin and other biomimetic materials, say University of Delaware researchers whose work appears in the Sept. 19 issue of Science.

Described as containing "the first known protein [with] both collagenous and elastin-like domains," byssal threads help mussels latch onto rocks, oil rigs, super-tankers and docks, the UD researchers say. Not surprisingly, mussels "create a major fouling problem on economically important surfaces exposed to the sea," says J. Herbert Waite, professor of marine biochemistry in UD's College of Marine Studies.

Byssal threads feature "a stiff tether" at one end and a "shock absorber" on the end protruding from the mussel foot, explains graduate student Kathryn J. Coyne, lead author of the Science article, along with postdoctoral research associate Xiao-Xia Qin and Waite. This gradual transition, from one material to another, gives byssal threads a surprising mix of properties.

"If a byssal thread were simply a stiff stick attached to an elastic tube, it wouldn't have an outside chance of surviving these relentless tidal beatings," Waite notes. "In fact, the collagen in byssal threads goes from being a stiff material, to something that's very stretchy--without any sudden transitions." It's not yet feasible to manufacture materials featuring such gradual transitions, Waite says. But, he adds, "It's fun to dream about versatile new materials for a whole host of products--from steel-belted radials to shoes, which must be soft and flexible, yet tough enough to pound the pavement." Waite emphasizes that his current work primarily provides fundamental insights into the molecular construction of byssal threads.

In the future, however, a better understanding of byssal threads might help scientists design biomaterials that take advantage of their remarkable properties, says Harold Slavkin, director of the National Institute of Dental Research, one of the National Institutes of Health, which sponsored the UD study. "Insight into the molecular structure that makes the byssus strong yet flexible might suggest, for example, new strategies for designing more comfortable and pliable artificial skin," Slavkin says.

Curious Forms of Collagen

To find out what makes byssal threads so special, Qin and Waite first isolated two key collagens: Col-P and Col-D. They used pepsin, an enzyme secreted by stomach cells of vertebrates, to pinpoint the collagens. Unlike most proteins, Waite says, Col-P and Col-D don't break apart in response to pepsin. Since pepsin works best in an acidic environment, researchers simply placed byssal threads and pepsin in a weak solution of acetic acid. "Col-P and Col-D were the only proteins detectable after pepsinization," Waite explains. "Within byssal threads, these two collagens are distributed in a complementary gradient, with Col-P predominant in the elastic, proximal region, near the foot of the mussel, and more Col-D at the far, or distal end."

The UD team also examined the protein precursors for Col-P and Col-D, found in the mussel foot, where byssal threads are produced. Specific antibodies--proteins designed to detect and fight off foreign molecules by binding with them--helped Coyne target preCol-P. First, messenger RNA (ribonucleic acid) containing the genetic code for the protein was extracted from mussel foot tissue. Next, RNA was converted to the more stable DNA (deoxyribonucleic acid) form and cloned into bacteria, which expressed the protein encoded by the mussel's RNA. Designer antibodies, produced by a laboratory animal injected with Col-P, quickly latched onto the protein precursor expressed by bacterial clones.

Three Major Domains

The preCol-P in byssal threads contains three major domains, Coyne says. The middle section of the protein precursor consists of a tough collagen-based domain, flanked on either side by a pair of elastin-like regions. These stretchy domains are then framed at each end by sections rich in the amino acid, histidine.

The rubbery sections of preCol-P resemble bovine elastin, which is "very similar" to human elastin, Coyne reports. "Elastins typically are found in the skin and arteries of vertebrate species only," she notes. "The presence of these types of sequences in proteins from an invertebrate species is unusual."

The elastin-like regions of preCol-P also contained high levels of glycine and alanine--the amino acids most prevalent in two forms of protein in spider silk, Waite says. Although the structural similarity between preCol-P and spider silk still must be verified, Waite says the possibility should interest biochemists. "Spider silk is so thin, it has been difficult for anyone but crystallographers to deal with it," he says. "Byssal threads could turn out to be an interesting substitute, or model for studying some aspects of spider silk."

Curiously, the collagenous regions of preCol-P contain a missing glycine. "When a deletion like this is found in other structural collagens," Waite says, "it's certainly lethal to the animal. So, it's quite fascinating to find a missing glycine in a perfectly functional collagen subjected to great stress and strain in marine environments." It's possible, Waite speculates, that the missing glycine creates a 35-degree "kink" or bend in the collagen. But, he adds, "how that might contribute to the stretchiness of the protein is anybody's guess."

Two histidine-rich domains, located at each end of preCol-P, may play a role in forming protein-zinc complexes, Qin says. Whenever histidine-rich domains occur in proteins, they usually bind with metal. In blood, for instance, histidine-loaded glycoprotein binds with zinc. In byssal threads, she says, these domains may react with metals to produce strong "bridges," which link up linear arrays of collagen. Breaks in some of these cross-linked sections appear to be promptly repaired, Waite says. "This is totally different from how vertebrate collagens form fibers in nature," he notes. "Bridge formation seems to be reversible, so that if you pull them apart, they reform when you bring them back into contact."

Biomedical or consumer materials based on byssal threads are "a long way off," Waite says, but the UD findings suggest some tantalizing possibilities. "What this study contributes, at this point, is a completely new way of looking at the potential properties of structural collagen--the human body's most abundant protein," he says.


Story Source:

The above story is based on materials provided by University Of Delaware. Note: Materials may be edited for content and length.


Cite This Page:

University Of Delaware. "Wonder Thread: UD Scientists Report First Protein With Collagen And Elastin-Like Domains." ScienceDaily. ScienceDaily, 23 September 1997. <www.sciencedaily.com/releases/1997/09/970923033835.htm>.
University Of Delaware. (1997, September 23). Wonder Thread: UD Scientists Report First Protein With Collagen And Elastin-Like Domains. ScienceDaily. Retrieved September 22, 2014 from www.sciencedaily.com/releases/1997/09/970923033835.htm
University Of Delaware. "Wonder Thread: UD Scientists Report First Protein With Collagen And Elastin-Like Domains." ScienceDaily. www.sciencedaily.com/releases/1997/09/970923033835.htm (accessed September 22, 2014).

Share This



More Health & Medicine News

Monday, September 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Liberia Pleads for Help to Fight Ebola

Liberia Pleads for Help to Fight Ebola

AP (Sep. 22, 2014) Liberia's finance minister is urging the international community to quickly follow through on pledges of cash to battle Ebola. Bodies are piling up in the capital Monrovia as the nation awaits more help. (Sept. 22) Video provided by AP
Powered by NewsLook.com
Ebola Doctor Says Border Controls Critical

Ebola Doctor Says Border Controls Critical

AP (Sep. 22, 2014) A Florida doctor who helped fight the expanding Ebola outbreak in West Africa says the disease can be stopped, but only if nations quickly step up their response and make border control a priority. (Sept. 22) Video provided by AP
Powered by NewsLook.com
Global Ebola Aid Increasing But Critics Say It's Late

Global Ebola Aid Increasing But Critics Say It's Late

Newsy (Sep. 21, 2014) More than 100 tons of medical supplies were sent to West Africa on Saturday, but aid workers say the global response is still sluggish. Video provided by Newsy
Powered by NewsLook.com
Sierra Leone in Lockdown to Control Ebola

Sierra Leone in Lockdown to Control Ebola

AP (Sep. 21, 2014) Sierra Leone residents remained in lockdown on Saturday as part of a massive effort to confine millions of people to their homes in a bid to stem the biggest Ebola outbreak in history. (Sept. 20) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins