Tough Tendons
MUSSEL BYSSUS HAS COLLAGEN WITH SILK-LIKE DOMAINS*
- From the ‡College of Marine Studies and Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716 and the §College of Marine Studies, University of Delaware, Lewes, Delaware 19958
Abstract
The primary structure of the α-chain of preCol-D (molecular mass = 80 kDa), a tanned collagenous protein predominating in the distal portion of the byssal threads of the musselMytilus edulis, was deduced from cDNA to encode an unprecedented natural block copolymer with three major domain types: a central collagen domain flanked by fibroin-like domains and followed by histidine-rich termini. The fibroin-like domains have sequence motifs that strongly resemble the crystalline polyalanine-rich and amorphous glycine-rich regions of spider dragline silk fibroins. The terminal regions resemble the histidine-rich domains of a variety of metal-binding proteins. The silk domains may toughen the collagen by increasing its strength and extensibility. PreCol-D expression is limited to the mussel foot, which contains a longitudinal gradient of preCol-D mRNA. This gradient increases linearly in the proximal to distal direction and reaches a maximum just before the distal depression of the foot.
Footnotes
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↵* Supported by Grants from the National Institutes of Health (DE 10042) and the Office of Naval Research (N00014-96-1-0812 and N00014-96-1-1205) (to J. H. W.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) AF029249.
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↵¶ To whom correspondence should be addressed. Fax: 302-831-6335; E-mail: hwaite{at}udel.edu.
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↵1 The abbreviations used are: Col-P, proximal thread collagen; Col-D, distal thread collagen; preCol, byssal precursor collagens; DOPA, 3,4-dihydroxyphenylalanine; NC-D′, noncollagenous peptide from preCol-D; PCR, polymerase chain reaction; HPLC, high pressure liquid chromatography; bp, base pair.
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- Received August 11, 1997.
- Revision received October 1, 1997.
