Sodium ion-driven serine/threonine transport in Porphyromonas gingivalis

Abstract

Porphyromonas gingivalis is an asaccharolytic, gram-negative bacterium that relies on the fermentation of amino acids for metabolic energy. When grown in continuous culture in complex medium containing 4 mM (each) free serine, threonine, and arginine, P. gingivalis assimilated mainly glutamate/glutamine, serine, threonine, aspartate/asparagine, and leucine in free and/or peptide form. Serine and threonine were assimilated in approximately equal amounts in free and peptide form. We characterized serine transport in this bacterium by measuring uptake of the radiolabeled amino acid in washed cells of P. gingivalis energized with a tetrapeptide not containing serine. Serine was transported by a ..