Phillips, C. B. | bioRxiv Science

bioRxiv2023

Whole genome assembly and annotation of the clover root weevil (Sitona obsoletus) using a combination of Illumina, 10X Genomics and MinION sequencing

Weevils are a highly diversified taxon, comprising about 70,000 described species that include many agricultural pests, biological control agents, and nutrient recyclers. Despite their importance and vast diversity, the number of sequenced genomes for the weevil family is still low (n=15). Here, we present a high-quality and contiguous genome assembly of Sitona obsoletus (Coleoptera: Curculionidae: Entiminae), a widespread invasive forage pest that infests clover species (Trifolium spp.) worldwide. We sequenced, assembled, and annotated the S. obsoletus genome using a hybrid approach that employed Nanopore long reads, 10X Chromium linked reads, Illumina short reads for assembly, and mRNA short read sequencing of various developmental stages for annotation. Our final annotated genome has a size of 1.2 Gb, with an N50 length of 313.85 kb. Benchmarking analyses against conserved single-copy Orthologs (BUSCO) found that over 94% of the genes were complete from each of the three BUSCO databases (Eukaryota, Insecta, and Arthropoda). A total of 9,777 protein-coding genes were annotated using the MAKER2 pipeline, of which 65% were functionally annotated. The annotated repeat elements make up 84.26% of the genome. The high-quality annotated genome of the weevil will facilitate a wide range of genetic, genomic, and phylogenetic studies on invasive weevils, as well as other weevil species in the subfamily Entiminae.

genomics↗

bioRxiv2020

Mitochondrial copper and phosphate transporter specificity was defined early in the evolution of eukaryotes

Mitochondrial carrier family (MCF/SLC25) proteins are selective transporters that maintain the mitochondrial metabolome. Here we combine computational, biochemical and phenotypic approaches to understand substrate selectivity of SLC25A3. In mammals, SLC25A3 transports both copper and phosphate, yet in Saccharomyces cerevisiae the transport of these substrates is partitioned across two paralogs: PIC2, which transports copper, and MIR1, which transports phosphate. To understand whether the ancestral state of this transporter was a single promiscuous transporter that duplicated and gained selectivity, we explored the evolutionary relationships of PIC2 and MIR1 orthologs across the eukaryotic tree of life. Phylogenetic analyses reveal that PIC2-like and MIR1-like orthologs are present in all major eukaryotic supergroups, indicating that the gene duplication that created these paralogs occurred early in eukaryotic evolution. Frequent lineage-specific gene duplications and losses suggest that substrate specificity may be evolutionarily labile. To link this phylogenetic signal to protein function and resolve the residues involved in substrate selection, we used structural modelling and site-directed mutagenesis to identify PIC2 residues involved in copper and phosphate transport activities. Based on these analyses, we generated a Leu175Ala variant of mouse SLC25A3 that retains the ability to transport copper, but not phosphate, and rescues the cytochrome c oxidase defect in SLC25A3 knockout cells. Taken together, this work uses an evolutionary framework to uncover amino acids involved in substrate recognition by MCF proteins responsible for copper and phosphate transport.

evolutionary biology↗