Figure 1. Few high copy suppressors are found for conserved and consistently essential genes.

We gathered information on orthologous genes in nine additional taxa for which essentiality has been experimentally investigated. All genes listed are essential in E. coli; for each gene, the orthologue in other taxa is indicated as essential (E; white background), non-essential (N; light grey), associated with large fitness reduction (N*), or unknown (U). Cases in which there is no orthologue are indicated with an A (absent; dark grey background). For example, spoT, which is essential in E. coli, has been found to be essential in only four out of eight other taxa and is absent from one. The second column indicates the high copy suppressors that were isolated (genes for which suppressors were isolated are highlighted in light grey). In parentheses are high copy suppressors that were recovered from the screen but which were not analyzed further. A cladogram showing the evolutionary relationships of these taxa is shown at the top of the table. Abbreviations: S.ty, Salmonella typhi Ty2; A.ba, Acinetobacter baylyi; C.cr, Caulobacter crescentus NA100; F.tu, Francisella tularensis U112; S.pn, Streptococcus pneumonia TIGR4; B.su, Bacillus subtilis 168; S.au, Staphylococcus aureus 8325; M.ge, Mycoplasma genitalium G37; M.pu, Mycoplasma pulmonis UAB CTIP. a) No reciprocal best hit orthologue of ftsK exists in B. subtilis due to an apparent duplication (genes BSU16800 and BSU29805); neither gene is essential. b) No reciprocal best hit orthologue of plsC exists in F. tularensis due to an apparent duplication (FTN1749 and FTN1750); only FTN1749 is essential.