2-Oxoglutarate transport system in Staphylococcus aureus

Tynecka, Z Korona-Glowniak, I Los, R

Z. Tynecka et al., 2-Oxoglutarate transport system in Staphylococcus aureus, ARCH MICROB, 176(1-2), 2001, pp. 143-150

36

INGLESE

Article

Microbiology

ARCHIVES OF MICROBIOLOGY

0302-8933 → ACNP

176

1-2

2001

143 - 150

ISI

0302-8933(200107)176:1-2<143:2TSISA>2.0.ZU;2-O

2-[C-14]oxoglutarate uptake in resting cells of Staphylococcus aureus 17810 S occurs via two kinetically different systems: (1) a secondary, electrogen ic 2-oxoglutarate:H+ symporter (K-m=0.105 mM), energized by an electrochemi cal proton potential (Delta mu (+)(H)) that is generated by the oxidation o f endogenous amino acids and sensitive to ionophores, and (2) a Delta mu ()(H)-independent facilitated diffusion system (K-m=1.31 mM). The 2-oxogluta rate transport system of S. aureus 17810S can be classified as a new member of the MHS (metabolite:H+ symporter) family. This transporter takes up var ious dicarboxylic acids in the order of affinity: succinate = malate > fuma rate > 2-oxoglutarate > glutamate. Energy conservation with 2-oxoglutarate was studied in starved cells of strain 17810S. Initial transport of 2-oxogl utarate in these cells is energized by Delta mu (+)(H) generated via hydrol ysis of residual ATR Subsequent oxidation of the accumulated 2-oxoglutarate generates Delta mu (+)(H) for further, autoenergized transport of this 2-o xoacid and also for Delta mu (+)(H)-linked resynthesis of ATR In the cadmiu m-sensitive S. aureus 17810S, Cd2+ accumulation strongly inhibits energy co nservation with 2-oxoglutarate at the level of Delta mu (+)(H) generation, without direct blocking of the 2-oxoglutarate transport system or ATP synth ase complex. In the cadmium-resistant S. aureus 17810R, Cd2+ does not affec t energy conservation due to its extrusion by the Cd2+ efflux system (Cd2+- ATPase of P-type), which prevents Cd2+ accumulation.