Characterization of glutamine transport in Streptococcus mutans

Abstract

Glutamine transport in glucose‐energized cells of Streptococcus mutans Ingbritt exhibited Michaelis‐Menten‐type kinetics with a Vmax of 13.4 nmol/mg dry weight/min and a K1 of 4.1 μM. Diffusion of glutamine into de‐energized cells of S. mutans displayed similar type kinetics, with a Kt of 6.8 μM but with a markedly reduced Vmax of 53.9 pmol/mg dry weight/min. Glutamine transport in S. mutans is not proton motive force‐driven, as the intracellular accumulation of glutamine by energized cells far exceeded the thermodynamic limits of the proton motive force, and the dissipation of this proton motive force by gramicidin in a high K+ medium did not decrease the intracellular glutamine concentrati..