The Structure and Function of Ionotropic Receptors in Drosophila

Ni, Lina

doi:10.3389/fnmol.2020.638839

Cited by 54 publications

(50 citation statements)

References 119 publications

(382 reference statements)

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“…A powerful model to study olfactory receptor evolution is the Ionotropic receptor (Ir) repertoire, a protostomian chemosensory subfamily of ionotropic glutamate receptors (iGluRs) ( Benton et al, 2009 ; Croset et al, 2010 ; Ni, 2020 ; Rytz et al, 2013 ). Although Irs and iGluRs have limited amino acid sequence identity, their overall conserved (predicted) secondary and tertiary structural organization suggests that the chemosensory receptors share many mechanistic similarities with their iGluR ancestors ( Abuin et al, 2011 ).…”

Section: Introductionmentioning

confidence: 99%

Molecular reconstruction of recurrent evolutionary switching in olfactory receptor specificity

Prieto-Godino

Schmidt

Benton

2021

eLife

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Olfactory receptor repertoires exhibit remarkable functional diversity, but how these proteins have evolved is poorly understood. Through analysis of extant and ancestrally-reconstructed drosophilid olfactory receptors from the Ionotropic receptor (Ir) family, we investigated evolution of two organic acid-sensing receptors, Ir75a and Ir75b. Despite their low amino acid identity, we identify a common 'hotspot' in their ligand-binding pocket that has a major effect on changing the specificity of both Irs, as well as at least two distinct functional transitions in Ir75a during evolution. Moreover, we show that odor specificity is refined by changes in additional, receptor-specific sites, including those outside the ligand-binding pocket. Our work reveals how a core, common determinant of ligand-tuning acts within epistatic and allosteric networks of substitutions to lead to functional evolution of olfactory receptors.

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Section: Introductionmentioning

confidence: 99%

Molecular reconstruction of recurrent evolutionary switching in olfactory receptor specificity

Prieto-Godino

Schmidt

Benton

2021

eLife

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“…However, after including the complete chemoreceptor set, a remarkable evolutionary hallmark emerges in the D. silvatica lineage (Figures 6, 7, S3 and S4). Only a small group of Ir genes, probably involved in some essential animal chemoreception functions, such as coreceptors (Ir25a/8a related sequences), and the receptors involved in thermosensation and hygrosensation, and in amino acid taste inDrosophila (i.e., Ir93a and Ir76b related sequences) (Ni, 2021), seem to be fairly conserved between insects and spiders. Although this extreme feature is well known in arthropods, where most family copies cluster in species-specific clades in the phylogenetic trees, current analysis is the first that incorporate nearly complete information of most copies of these two families in a chelicerate.…”

Section: Phylogenetic Analysis Of the Chemoreceptor Genes In Arthropodsmentioning

confidence: 99%

Chromosome-scale assembly of the Canary Island endemic spider Dysdera silvatica (Arachnida, Araneae) sheds light on the origin and genome structure of chemoreceptor gene families in spiders

Escuer¹,

Pisarenco²,

Fernández-Ruiz³

et al. 2021

Preprint

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We present the chromosome-level genome assembly of Dysdera silvatica Schmidt, 1981, a nocturnal ground-dwelling spider endemic from the Canary Islands. The genus Dysdera has undergone a remarkable diversification in this archipelago mostly associated with shifts in the level of trophic specialization, becoming an excellent model to study the genomic drivers of adaptive radiations. The new assembly (1.37 Gb; and scaffold N50 of 174.2 Mb), was performed using the chromosome conformation capture scaffolding technique, represents a continuity improvement of more than 4,500 times with respect to the previous version. The seven largest scaffolds or pseudochromosomes cover 87% of the total assembly size and match consistently with the seven chromosomes of the karyotype of this species, including the characteristic large X chromosome. To illustrate the value of this new resource we performed a comprehensive analysis of the two major arthropod chemoreceptor gene families (i.e., gustatory and ionotropic receptors). We identified 545 chemoreceptor sequences distributed across all pseudochromosomes, with a notable underrepresentation in the X chromosome. At least 54% of them localize in 83 genomic clusters with a significantly lower evolutionary distances between them than the average of the family, suggesting a recent origin of many of them. This chromosome-level assembly is the first high-quality genome representative of the Synspermiata clade, and just the third among spiders, representing a new valuable resource to gain insights into the structure and organization of chelicerate genomes, including the role that structural variants, repetitive elements and large gene families played in the extraordinary biology of spiders.

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“…Here, we investigated the mechanisms ensuring the exclusive expression of members of a "model" cluster of three Drosophila melanogaster Ionotropic receptors (Irs), a gene family that encodes chemosensory receptors distantly related to ionotropic glutamate receptors (7)(8)(9). This gene array, Ir75c, Ir75b, and Ir75a (organized 5′ to 3′, spanning <10 kb) (Fig.…”

Section: Introductionmentioning

confidence: 99%

Olfactory receptor–dependent receptor repression in Drosophila

et al. 2021

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In olfactory systems across phyla, most sensory neurons express a single olfactory receptor gene selected from a large genomic repertoire. We describe previously unknown receptor gene–dependent mechanisms that ensure singular expression of receptors encoded by a tandem gene array [Ionotropic receptor 75c (Ir75c), Ir75b, and Ir75a, organized 5′ to 3′] in Drosophila melanogaster. Transcription from upstream genes in the cluster runs through the coding region of downstream loci and inhibits their expression in cis, most likely via transcriptional interference. Moreover, Ir75c blocks accumulation of other receptor proteins in trans through a protein-dependent, posttranscriptional mechanism. These repression mechanisms operate in endogenous neurons, in conjunction with cell type–specific gene regulatory networks, to ensure unique receptor expression. Our data provide evidence for inter-olfactory receptor regulation in invertebrates and highlight unprecedented, but potentially widespread, mechanisms for ensuring exclusive expression of chemosensory receptors, and other protein families, encoded by tandemly arranged genes.

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The Structure and Function of Ionotropic Receptors in Drosophila

Cited by 54 publications

References 119 publications

Molecular reconstruction of recurrent evolutionary switching in olfactory receptor specificity

Molecular reconstruction of recurrent evolutionary switching in olfactory receptor specificity

Chromosome-scale assembly of the Canary Island endemic spider Dysdera silvatica (Arachnida, Araneae) sheds light on the origin and genome structure of chemoreceptor gene families in spiders

Olfactory receptor–dependent receptor repression in Drosophila

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