Structural diversity and evolution of the N-terminal isoform-specific region of ecdysone receptor-A and -B1 isoforms in insectsReportar como inadecuado

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BMC Evolutionary Biology

, 10:40

First Online: 12 February 2010Received: 21 August 2009Accepted: 12 February 2010


BackgroundThe ecdysone receptor EcR regulates various cellular responses to ecdysteroids during insect development. Insects have multiple EcR isoforms with different N-terminal A-B domains that contain the isoform-specific activation function AF-1 region. Although distinct physiologic functions of the EcR isoforms have been characterized in higher holometabolous insects, they remain unclear in basal direct-developing insects, in which only A isoform has been identified. To examine the structural basis of the EcR isoform-specific AF-1 regions, we performed a comprehensive structural comparison of the isoform-specific region of the EcR-A and -B1 isoforms in insects.

ResultsThe EcR isoforms were newly identified in 51 species of insects and non-insect arthropods, including direct-developing ametabolous and hemimetabolous insects. The comprehensive structural comparison revealed that the isoform-specific region of each EcR isoform contained evolutionally conserved microdomain structures and insect subgroup-specific structural modifications. The A isoform-specific region generally contained four conserved microdomains, including the SUMOylation motif and the nuclear localization signal, whereas the B1 isoform-specific region contained three conserved microdomains, including an acidic activator domain-like motif. In addition, the EcR-B1 isoform of holometabolous insects had a novel microdomain at the N-terminal end.

ConclusionsGiven that the nuclear receptor AF-1 is involved in cofactor recruitment and transcriptional regulation, the microdomain structures identified in the isoform-specific A-B domains might function as signature motifs and-or as targets for cofactor proteins that play essential roles in the EcR isoform-specific AF-1 regions. Moreover, the novel microdomain in the isoform-specific region of the holometabolous insect EcR-B1 isoform suggests that the holometabolous insect EcR-B1 acquired additional transcriptional regulation mechanisms.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2148-10-40 contains supplementary material, which is available to authorized users.

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Autor: Takayuki Watanabe - Hideaki Takeuchi - Takeo Kubo


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