pH dependence of the Coxiella burnetii glutamate transport system - PubMed (original) (raw)

pH dependence of the Coxiella burnetii glutamate transport system

T Hackstadt et al. J Bacteriol. 1983 May.

Abstract

The transport of glutamate, apparently a primary energy source for Coxiella burnetii, has been examined. C. burnetii is shown to possess a pH-dependent active transport system for L-glutamate with an apparent Kt of 61.1 microM and Vmax of 8.33 pmol/s per mg at pH 3.5. Both L-glutamine and L-asparagine competitively inhibited transport of glutamate, but D-glutamate, L-aspartate, L-glutamate-gamma-methyl ester, methionine sulfoximine, or alpha-ketoglutarate did not compete. This transport system is both temperature and energy dependent. Uptake of glutamate is highly sensitive to uncouplers of oxidative phosphorylation such as 2,4-dinitrophenol and carbonyl cyanide-m-chlorophenyl hydrazone that decrease the proton motive force across the cytoplasmic membrane. ATPase inhibitors such as dicyclohexylcarbodiimide or metabolic poisons such as KCN, NaF, or arsenite were much less effective as inhibitors of glutamate transport. Uptake of glutamate did not appear to be coupled to Na+ symport as in Escherichia coli since no monovalent cation requirement could be demonstrated. Instead, the Vmax of glutamate transport showed good correlation with the transmembrane pH gradient (delta pH). From these results, we propose that L-glutamate transport by C. burnetii is energized via a proton motive force.

PubMed Disclaimer

Similar articles

Cited by

References

    1. J Bacteriol. 1983 May;154(2):591-7 - PubMed
    1. J Biol Chem. 1965 Feb;240:863-9 - PubMed
    1. J Bacteriol. 1967 Mar;93(3):1009-16 - PubMed
    1. J Bacteriol. 1969 Oct;100(1):329-36 - PubMed
    1. Physiol Rev. 1970 Oct;50(4):637-718 - PubMed

MeSH terms

Substances

LinkOut - more resources