Properties of a Na+/galactose (glucose) symport system in Vibrio parahaemolyticus

Biochim Biophys Acta. 1996 Mar 13;1279(2):149-56. doi: 10.1016/0005-2736(95)00252-9.


We have investigated galactose transport in a mutant strain of Vibrio parahaemolyticus that lacks a glucose-PTS (phosphoenolpyruvate:carbohydrate phosphotransferase system) and a trehalose-PTS. Cells of the V. parahaemolyticus actively transported D-galactose and Na+ greatly stimulated the transport. Maximum stimulation of D-galactose transport activity was observed at 10mM NaCl, and Na+ could be replaced with Li+. Addition of galactose to the cell suspension under anaerobic conditions elicited Na+ uptake. Therefore, we conclude that this organism accomplishes galactose transport by a Na+/solute symport mechanism. Judging from inhibition results, D-galactose, D-glucose and to a lesser extent alpha-D-fucose are substrates of this transport system. The Na+/galactose symport system exhibited a high affinity for D-galactose (Km: 40 microM) and showed a relatively lower affinity for D-glucose (Km: 420 microM), but the maximum velocities for galactose and glucose transport were almost same (about 52 nmol/min per mg protein). The Na+/D-galactose symport system was induced by either D-galactose or alpha-D-fucose, and repressed by D-glucose.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport / drug effects
  • Galactose / metabolism*
  • Glucose / metabolism*
  • Ion Transport
  • Kinetics
  • Monosaccharide Transport Proteins / metabolism*
  • Salts / pharmacology
  • Sodium / metabolism*
  • Sodium Chloride / pharmacology
  • Substrate Specificity
  • Vibrio parahaemolyticus / growth & development
  • Vibrio parahaemolyticus / metabolism*


  • Monosaccharide Transport Proteins
  • Salts
  • Sodium Chloride
  • Sodium
  • Glucose
  • Galactose