Fig. 1: Four bacterial clades that independently lost chromosomal rrn operons.
From: Bacteria can maintain rRNA operons solely on plasmids for hundreds of millions of years
a–d Maps of the rrn plasmids of a Persicobacteraceae species, b Treponema saccharophilum, c Aureimonas ureilytica11, and d Oecophyllibacter saccharovorans18. Solid and dotted inner arcs show rrn operon with or without tRNA genes, respectively. rRNA and tRNA genes are shown by black arrows. rep, parAB, bioABFCD, and sig genes encode plasmid replication initiators, partitioning proteins, biotin synthetic proteins, and sigma factors, respectively. Genes whose products belong the same function are presented in the same colors. Note that repA1A2A3 of Persicobacter diffluens and repA1’A2’ of Persicobacter psychrovividus have no sequence similarity. e Comparative synteny map of rrn plasmids of the Persicobacteraceae species. f, g Phylogenetic trees of rRNA genes and conserved single-copy protein-coding genes of f Persicobacteraceae species and g T. saccharophilum and their related species. Pink indicates bacteria without chromosomal rrn operons. Light blue indicates bacteria with chromosomal rrn operons. Numbers in parentheses are numbers of chromosomal rrn operons. Asterisks indicate genomes whose assembly levels are scaffold. Bootstrap values of >50% are shown. Scale bars indicate substitution numbers per site. See Supplementary Data 1–3 for strain names, conserved single-copy protein-coding genes, and results of topological test, respectively.
