Exploring the Selfish Nature of Transposons and Their Role in Ubiquity and Abundance in Life
This study investigates the "selfish" nature of transposons in relation to their ubiquity and abundance across various genomic contexts. By analyzing the prevalence of transposons, conserved proteins, and essential genes, the research highlights the complexities of evolutionary competition. Key findings suggest that while some proteins like RuBisCo dominate in certain ecosystems, transposons represent a more universal element of genomic diversity, challenging traditional views on genomic essentiality and abundance.
Exploring the Selfish Nature of Transposons and Their Role in Ubiquity and Abundance in Life
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Presentation Transcript
Are transposons selfish? Ramy Aziz Rob Edwards
What does it mean to “win”? • Ubiquity: (omnipresence/ universality essentiality) • For the purpose of this study, the ubiquity of x is calculated as the number of “sets” to which x belongs • x= (gene, protein, function, protein-encoding gene, enzyme) • @sets = (genomes, metagenomes, biomes) • Abundance: (profusion ‘fertility/ promiscuity’) • The abundance of x is calculated as the (average) number of times x is represented in a particular set
Counting CDS in genomes ☺ CDS fully sequenced ☺ one copy per function (more == paralogs) So, just collect all genomes, extract all cds, count functions, and get results. ☹ Sequenced genomes do not represent life, but rather human-centered interests in life.
Counting EGTs in metagenomes • Environmental gene tag (EGT) comes from one organism and represents one or more functions. • ☺ Counts ∝ abundance • ☹ Counts depend on: • Abundance • Gene length • Metagenome sample size ($$) ☹ Up 90% with no BLAST hits
Biology Textbooks • The most abundant protein: RuBisCo* • How so? It’s the enzyme with the highest copy number in ecosystems (or with highest total mass). • Is it the most ubiquitous? No! It’s almost only in photosynthetic organisms. • Is its gene the most abundant? No! Most genomes lack it. *ribulose-1,5-bis phosphate carboxylase
And the winner is … • Hypothetical protein • aka • Conserved protein • Unknown protein • Protein predicted by Glimmer • Very hypothetical protein • No name
Why transposons? • Essential for life • Cheaters win Two hypotheses:
Metagenomes … fertility Pearson Corr. 0.524 eco-essentiality
Metagenomes … fertility Habitat -specific Life essentials Pearson Corr. 0.524 eco-essentiality
Tn per prophage 30 All phages Number of phage Defective phages 20 Suspected viable phages 10 Viable phages 0 2 4 6 8 10 12 14 16 Number of Tn per phage
Why transposons? • Essential for life ✔ • Cheaters win ? Two hypotheses: