The hub protein loquacious connects the microRNA and short interfering RNA pathways in mosquitoes.
Bottom Line: Conversely, Loqs-PB alone interacted with mosquito dicer-1 and was essential for full miRNA production.Mosquito Loqs interacted with both argonaute 1 and 2 in a manner independent of its interactions with dicer.We conclude that the functional specialization of Loqs-PD in Drosophila is a recently derived trait, and that in other dipterans, including the medically important mosquitoes, Loqs-PA participates in both the miRNA and endo-siRNA based pathways.
Affiliation: Fralin Life Science Institute and Department of Entomology, Virginia Tech, Blacksburg, VA 24061, USA.Show MeSH
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Mentions: Our failure to identify a loqs-rd transcript in Ae. aegypti suggests that this isoform may not be conserved amongst all dipterans. To determine the potential for dipterans outside of Drosophila to encode Loqs-PD, we performed a two-step blast-based search of various dipteran genome assemblies. In the first step, the D. melanogaster Loqs protein sequence was used to identify loqs orthologs in the relevant genomes via blastp or tblastn. In the second step, 15–20 residues corresponding to the end of exon 4 for each species were used to query its own genome assembly (tblastn). After manual inspection of the aligned regions, the coding potential of read-through into the intronic region was determined. As shown in Figure 2A, the unique Loqs-PD tail region is conserved in almost all drosophilids, with only D. willistoni containing a premature stop codon limiting potential translation to just six additional amino acids. In contrast, the ability of other dipterans to generate Loqs-PD tail regions appeared to be limited, with little apparent conservation (Figure 2B). While the malaria mosquito, Anopheles gambiae, has the potential to encode an additional 68 amino acids following the exon 4 splice donor site, this region is not conserved amongst other Anophelines (Supplementary Figure S2). As stated earlier, while Ae. aegypti has the potential to encode an additional 41 amino acids, no evidence of such a transcript could be found. We conclude that Ae. aegypti, and likely most non-drosophilid dipterans, do not encode a Loqs-PD isoform and thus must use an alternative strategy to coordinate processing and/or loading of endo-siRNAs.
Affiliation: Fralin Life Science Institute and Department of Entomology, Virginia Tech, Blacksburg, VA 24061, USA.