Table 2 Genes inferred as uniquely essential in Shigella
Gene(s) | Function [49] | Support for Different Physiological Roles in E. coli and Shigella |
|---|---|---|
lysS | aminoacyl tRNA synthetase, tRNA modification | The lysU functional homologue is absent in Shigella [45] |
proABC | proline biosynthesis | The active proline transporter putP is absent from Shigella [46]. The cryptic transporter proY may be silent, as observed in Salmonella [47], possibly necessitating proline biosynthesis |
ackA pta aceEF pykF | acetate kinase phosphotransacetylase pyruvate dehydrogenase pyruvate kinase | All affect acetate accumulation [66] and utilization [23], which is required for robust growth (Shigella lacks the acetyl CoA synthetase present in E. coli K12 [67]) |
rfbA, rfbF, rfbG, rfc, and rfbI | sugar nucleotide biosynthesis for LPS | All except rfbA lack E. coli K12 orthologues, as this locus has been replaced by the laterally transferred wbb locus [48] |
cysM | cysteine synthase B | ORFs in cysteine synthase A also depleted for inserts; 4 out of 5 sulfate ABC transporters depleted for inserts (see main text) |
tufB | elongation factor EF-Tu | tufB and lepA (next entry) both are involved in translation elongation; the other ORF involved, tufA, is depleted for inserts (see main text) |
lepA | elongation factor 4 | See above |
spr | murein DD-endopeptidase | None known |
rsxB | soxR-reducing complex | None known |