We have used differential display to identify genes that are regulated by juvenile hormone in the epidermis of the beetle Tenebrio molitor. One of the genes encodes T. molitor chitinase 5 (TmChit5), a chitinase possessing an unusual structure. Sequence analysis of TmChit5 identified five ‘chitinase units’ of approx. 480 amino acids with similarity to chitinase family 18. These units are separated by less conserved regions containing putative PEST (rich in proline, glutamic acid, serine and threonine) sequences, putative chitin-binding domains and mucin domains. Northern-blot analysis identified a single transcript of approx. 9kb, whose abundance correlated with that of 20-hydroxyecdysone during metamorphosis. Injection of pupae with 20-hydroxyecdysone alone, or in combination with cycloheximide, indicated that TmChit5 expression is directly induced by the hormone. Further experiments indicated that methoprene (a juvenile hormone analogue) indirectly induced TmChit5 mRNA expression. On the basis of the present results and previous studies, we propose a molecular mechanism for cuticle digestion during the moulting process.
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September 2002
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Research Article|
September 15 2002
A novel putative insect chitinase with multiple catalytic domains: hormonal regulation during metamorphosis
Véronique ROYER;
Véronique ROYER
Unité Mixte de Recherche CNRS 5548, Développement-Communication Chimique, Université de Bourgogne, 6 boulevard Gabriel, 21000 Dijon, France
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Stéphane FRAICHARD;
Stéphane FRAICHARD
Unité Mixte de Recherche CNRS 5548, Développement-Communication Chimique, Université de Bourgogne, 6 boulevard Gabriel, 21000 Dijon, France
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Hervé BOUHIN
Hervé BOUHIN
1
Unité Mixte de Recherche CNRS 5548, Développement-Communication Chimique, Université de Bourgogne, 6 boulevard Gabriel, 21000 Dijon, France
1To whom correspondence should be addressed (e-mail hbouhin@u-bourgogne.fr).
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Publisher: Portland Press Ltd
Received:
November 30 2001
Revision Received:
May 07 2002
Accepted:
June 11 2002
Accepted Manuscript online:
June 11 2002
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2002
2002
Biochem J (2002) 366 (3): 921–928.
Article history
Received:
November 30 2001
Revision Received:
May 07 2002
Accepted:
June 11 2002
Accepted Manuscript online:
June 11 2002
Citation
Véronique ROYER, Stéphane FRAICHARD, Hervé BOUHIN; A novel putative insect chitinase with multiple catalytic domains: hormonal regulation during metamorphosis. Biochem J 15 September 2002; 366 (3): 921–928. doi: https://doi.org/10.1042/bj20011764
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