Research article summary (published Jun 2006):

The design of silk fiber composition in moths has been conserved for more than 150 million years.

Full Abstract

The silk of caterpillars is secreted in the labial glands, stored as a gel in their lumen, and converted into a solid filament during spinning. Heavy chain fibroin (H-fibroin), light chain fibroin (L-fibroin), and P25 protein constitute the filament core in a few species that have been analyzed. Identification of these proteins in Yponomeuta evonymella, a moth from a family which diverged from the rest of Lepidoptera about 150 million years ago, reveals that the mode of filament construction is highly conserved. It is proposed that association of the three proteins is suited for long storage of hydrated silk dope and its rapid conversion to filament. Interactions underlying these processes depend on conserved spacing of critical amino acid residues that are dispersed through the L-fibroin and P25 and assembled in the short ends of the H-fibroin molecule. Strength, elasticity, and other physical properties of the filament are determined by simple amino acid motifs arranged in repetitive modules that build up most of the H-fibroin. H-Fibroin synergy with L-fibroin and P25 does not interfere with motif diversification by which the filament acquires new properties. Several types of motifs in complex repeats occur in the silks used for larval cobwebs and pupal cocoons. Restriction of silk use to cocoon construction in some lepidopteran families has been accompanied by simplification of H-fibroin repeats. An extreme deviation of the silk structure occurs in the Saturniidae silkmoths, which possess modified H-fibroin and lack L-fibroin and P25.

Author information

Author/s: Yonemura, Naoyuki (N); Sehnal, Frantisek (F);

Affiliation: Institute of Entomology and Faculty of Biological Sciences, Academy of Sciences, University of South Bohemia, Branisovská 31, 370 05, Ceské Budejovice, Czech Republic.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Journal of molecular evolution (J Mol Evol), published in Germany. (Language: eng)

Reference: 2006-Jul; vol 63 (issue 1) : pp 42-53

Dates: Created 2006/06/30; Completed 2006/09/27; Revised 2006/11/15;

PMID: 16755355, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Amino Acid Motifs Amino Acid Sequence Animals Base Sequence Conserved Sequence DNA, Complementary - isolation & purification Evolution, Molecular Fibroins - biosynthesis; chemistry; genetics Glycoproteins - genetics Insect Proteins - genetics

Insect Proteins - genetics Molecular Sequence Data Moths - genetics; metabolism Sequence Homology, Amino Acid Sequence Homology, Nucleic Acid Silk - biosynthesis Species Specificity Structural Homology, Protein Structure-Activity Relationship Time

Associated Chemicals: DNA, Complementary (0) ; Glycoproteins (0) ; Insect Proteins (0) ; L-chain, fibroin protein, insect (0) ; P25 protein, Galleria mellonella (0) ; Silk (0) ; Fibroins (9007-76-5)

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