Figure 1. Many E. coli genes efficiently complement lethal growth defects in their yeast counterparts.

(A) Yeast and E. coli share hundreds of genes, 58 of which are essential in yeast and have clear 1:1 orthologs in either species. E. coli genes were cloned into a yeast expression vector under the control of a GPD promoter. 51 of these 58 E. coli genes provided informative assays for replaceability in yeast. Initial results from these complementation assays revealed that 25 of 51 (~49%) E. coli genes could functionally replace their orthologous yeast counterparts. (B) Complementation assays were performed in two different yeast strain backgrounds, as shown for representative assays. In the case of a yeast strain with a temperature-sensitive allele of the yeast gene Sc-cdc8, cells carrying the empty vector control grow at the permissive-temperature (25°C, yeast protein active) but not the restrictive-temperature (36°C, yeast protein inactive), unlike cells expressing the E. coli ortholog (Ec-tmK), indicating that the E. coli gene can functionally replace the yeast gene. In the case of yeast heterozygous diploid (Sc-ths1Δ/Sc-THS1) deletion strain, cells are sporulated and haploid progeny grown on selective medium (-Ura -Arg -His -Leu + Can) in the absence (yeast gene present) or presence of G418 (200 μg/ml) (yeast gene absent). Cells expressing the E. coli ortholog (Ec-thrS) grow on G418-containing medium, unlike cells carrying the empty vector control, indicating successful complementation. (C) Haploid yeast gene deletion strains carrying plasmids expressing functionally replacing E. coli genes (red solid-lines) generally exhibit comparable growth rates to the wild type parental yeast strain BY4741 (black dotted-lines). The empty vector control (grey solid-line) showed no such growth rescue in the presence of G418. Mean and standard deviation plotted with N = 3.

DOI: http://dx.doi.org/10.7554/eLife.25093.003

Figure 1—figure supplement 1. Complementation assays performed in a 96-well format in two different yeast strain backgrounds (Supplementary file 1).

(A and B) Magic marker heterozygous diploid deletion yeast strains expressing E. coli genes were sporulated and the sporulation mix was spotted on magic marker agar medium (-Ura -Arg -His -Leu + Can) with (yeast gene absent) or without (yeast gene present) G418 (200 μg/ml). (C) Temperature-sensitive haploid yeast strains expressing E. coli genes grown at permissive temperature (25°C) (yeast protein active) and at restrictive temperature (36°C) (yeast protein inactive) on -Ura agar medium with G418 (200 μg/ml). Empty vector containing yeast cells were used as negative control for the experiment. (D) Haploid yeast gene deletion strains carrying plasmids expressing functionally replacing E. coli genes (red solid-lines) generally exhibit comparable growth rates to the wild type parental yeast strain BY4741 (black dotted-lines) as grown in YPD liquid medium in the presence of G418 (300 μg/ml). Mean and standard deviation plotted with N = 3.

DOI: http://dx.doi.org/10.7554/eLife.25093.004

Figure 1—figure supplement 2. Constitutive plasmid expression of yeast genes efficiently replaced the corresponding genomic copies for 6 non-replaceable alleles.

Bacterial orthologs of the yeast genes, Sc-RRP3, Sc-PGS1, Sc-SRP54, Sc-PCM1 and Sc-HSP60 did not show functional replacement when expressed from a constitutive GPD promoter. We expressed the corresponding yeast genes in a similar fashion under the control of the constitutive GPD promoter. All the tested yeast genes functionally replaced the corresponding yeast gene deletions. Empty vector containing yeast cells were used as negative control for the experiment.

DOI: http://dx.doi.org/10.7554/eLife.25093.005