Evolution of repetitive proteins: spider silks from Nephila clavipes (Tetragnathidae) and Araneus bicentenarius (Araneidae)

Spider silks are highly repetitive proteins, characterized by regions of polyalanine and glycine-rich repeating units. We have obtained two variants of the Spidroin 1 (NCF-1) silk gene sequence from Nephila clavipes. One sequence (1726 bp) was from a cloned cDNA, and the other (1951 bp) was from PCR...

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Bibliographic Details
Published in:Insect biochemistry and molecular biology 1998-03, Vol.28 (3), p.121-130
Main Authors: Beckwitt, Richard, Arcidiacono, Steven, Stote, Robert
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Araneus bicentenarius
Base Sequence
Cloning, Molecular
concerted evolution
DNA Primers - genetics
DNA, Complementary - genetics
Evolution, Molecular
fibroin
Fibroins
Insect Proteins
Molecular Sequence Data
Nephila clavipes
Polymerase Chain Reaction
Proteins - genetics
repetitive protein
Repetitive Sequences, Nucleic Acid
Sequence Homology, Amino Acid
Sequence Homology, Nucleic Acid
Silk
Species Specificity
spider silk
Spiders - genetics
spidroin
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Summary:Spider silks are highly repetitive proteins, characterized by regions of polyalanine and glycine-rich repeating units. We have obtained two variants of the Spidroin 1 (NCF-1) silk gene sequence from Nephila clavipes. One sequence (1726 bp) was from a cloned cDNA, and the other (1951 bp) was from PCR of genomic DNA. When these sequences are compared with each other and the previously published Spidroin 1 sequence, there are differences due to sequence rearrangements, as well as single base substitutions. These variations are similar to those that have been reported from other highly repetitive genes, and probably represent the results of unequal cross-overs. We have also obtained 708 bp of sequence from PCR of genomic DNA from Araneus bicentenarius. This sequence shows considerable similarity to a dragline sequence (ADF-3) from A. diadematus, as well as Spidroin 2 (NCF-2) from N. clavipes. Minor but consistent differences in the repeating unit sequence between A. bicentenarius and A. diadematus suggest that concerted evolution or gene conversion processes are acting to maintain similarity among repeat units within a single gene.
ISSN:0965-1748
1879-0240
DOI:10.1016/S0965-1748(97)00083-0