ABSTRACT
Gene Slider helps visualize the conservation and entropy of orthologous DNA and protein sequences by presenting them as one long sequence logo that can be zoomed in and out of, from an overview of the entire sequence down to just a few residues at a time. A search function enables users to find motifs such as cis-elements in promoter regions by simply 'drawing' a sequence logo representation of the desired motif as a query. In addition to displaying user-supplied FASTA files, our demonstration version of Gene Slider loads and displays a rich database of 90 000+ conserved non-coding regions across the Brassicaceae indexed to the TAIR10 Col-0 Arabidopsis thaliana sequence. It also displays transcription factor binding sites, enabling easy identification of regions that are both conserved across multiple species and may contain transcription factor binding sites. AVAILABILITY AND IMPLEMENTATION: Freely available on the web at: http://www.bar.utoronto.ca/GeneSlider and also as an app on http://araport.org Website implemented in JavaScript and Processing.js with all major browsers supported. Source code available under GNU GPLv2 at SourceForge: https://sourceforge.net/projects/geneslider/ CONTACT: nicholas.provart@utoronto.ca.
Subject(s)
Computational Biology/methods , Position-Specific Scoring Matrices , Sequence Analysis, DNA/methods , Sequence Analysis, Protein/methods , Software , Binding Sites , Brassicaceae/genetics , Conserved Sequence , Databases, Genetic , Internet , Promoter Regions, Genetic , Transcription Factors/metabolismABSTRACT
Despite its poorly adapted codon usage, HIV-1 replicates and is expressed extremely well in human host cells. HIV-1 has recently been shown to package non-lysyl transfer RNAs (tRNAs) in addition to the tRNA(Lys) needed for priming reverse transcription and integration of the HIV-1 genome. By comparing the codon usage of HIV-1 genes with that of its human host, we found that tRNAs decoding codons that are highly used by HIV-1 but avoided by its host are overrepresented in HIV-1 virions. In particular, tRNAs decoding A-ending codons, required for the expression of HIV's A-rich genome, are highly enriched. Because the affinity of Gag-Pol for all tRNAs is nonspecific, HIV packaging is most likely passive and reflects the tRNA pool at the time of viral particle formation. Codon usage of HIV-1 early genes is similar to that of highly expressed host genes, but codon usage of HIV-1 late genes was better adapted to the selectively enriched tRNA pool, suggesting that alterations in the tRNA pool are induced late in viral infection. If HIV-1 genes are adapting to an altered tRNA pool, codon adaptation of HIV-1 may be better than previously thought.