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Positional cloning of silkworm white egg 2 ( w‐2 ) locus shows functional conservation and diversification of ABC transporters for pigmentation in insects
Author(s) -
Tatematsu Kenichiro,
Yamamoto Kimiko,
Uchino Keiro,
Narukawa Junko,
Iizuka Tetsuya,
Banno Yutaka,
Katsuma Susumu,
Shimada Toru,
Tamura Toshiki,
Sezutsu Hideki,
Daimon Takaaki
Publication year - 2011
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/j.1365-2443.2011.01490.x
Subject(s) - biology , bombyx mori , bombyx , drosophila melanogaster , antheraea pernyi , white (mutation) , genetics , mutant , atp binding cassette transporter , positional cloning , gene , transporter
The white , scarlet and brown genes of Drosophila melanogaster encode three half‐type ATP‐binding cassette (ABC) transporters. In Drosophila , precursors of ommochromes and pteridines are transported by White/Scarlet and White/Brown heterodimers, respectively. The white egg 2 ( w‐2 ) mutant of the silkworm, Bombyx mori , has white eggs and eyes because of lack of ommochrome granules in the serosa and eyes. Here, we report that the silkworm w‐2 locus encodes an ortholog of Drosophila scarlet . Our results indicate that Bombyx Scarlet forms a heterodimer with Bombyx White to transport ommochrome precursors, suggesting that formation of a White/Scarlet heterodimer and its involvement in the transport of ommochrome precursors are evolutionarily ancient and widely conserved traits in insects. Contrary to dipteran insects, white and scarlet were juxtaposed in a head‐to‐tail orientation in the silkworm genome, suggesting that the origin of white and scarlet was a tandem duplication of their ancestral transporter gene. In Bombyx , White is also essential for the transport of uric acid in larval epidermis. However, our results suggest that a Bombyx White/Scarlet heterodimer is not involved in this process. Our results emphasize the functional conservation and diversification of half‐type ABC transporter families in insects, which may contribute to their extremely diverse color patterns.