Table 2.
Summary of amino acid changes in E. faecium R446 (DAP-resistant) isolate compared to S447 (DAP susceptible)
| Predicted gene product | Nucleotide change in R446 | Predicted amino change in R446 | Comments |
|---|---|---|---|
| Cls | C→T | Arg218→Gln | A transmembrane protein predicted to be involved in phospholipid metabolism; the mutation is within the phospholipase D domain (two conserved phospholipase D domains are usually present in these enzymes) |
| YycG | C→T | Ser333→Leu | Putative histidine kinase of an essential two-component regulatory system that is conserved in most Firmicutes and is involved in cell wall homeostasis |
| Cfa | C→G reversion | Ala292→Glya | Cyclopropane synthase, which catalyzes the conversion of a double bond in a fatty acid to a cyclopropane ring (39) |
| RrmA | A→C | Ser76→Tyr | 23S rRNA methyltransferase (70) |
| SulP | C→T | His71→Tyr | Putative sulfate transporter and anti-sigma factor antagonist (STAS) domain (71) |
| XpaC | C→G reversion | His198→Aspb | Putative protein that mediates the hydrolysis of 5-bromo-4-chloroindolyl-phosphate bonds |
| PTS-EIIA member protein | T→A reversion | Asn118→ Lysc | Member of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), which plays a role in the uptake of carbohydrates (64) |
| Protein with an HD domain | A→G | Arg57→His | The HD domain defines a superfamily of enzymes that may possess phosphohydrolase activity and may be involved in nucleic acid metabolism and signal transduction (41) |
The amino acid change in R446 is an apparent reversion to the wild type, since the consensus sequence in position 292 of putative Cfa enzymes from other E. faecium strains whose genomes have been sequenced is glycine.
The amino acid change in R446 is also a reversion to the wild type, since the consensus sequence in position 198 of the predicted XpaC enzyme from other E. faecium strains whose genomes have been sequenced is aspartate.
The amino acid change in R446 is also a reversion to the wild type, since the consensus sequence in position 118 of the PTS transporters from other E. faecium strains whose genomes have been sequenced is lysine.