Inhibition Of Cell Division By Proline Analogues: Reversal by Proline and High Salinity

Abstract

Summary Six proline analogues were tested for their ability to inhibit cell division in N. bacillaris at low salinity. Two analogues, thiazolidine-4-carboxylic acid (T4C) and azetidine-2-carboxylic acid (A2C) were found to be effective inhibitors. Inhibition by 1 mM T4C was not readily reversed by L-proline while inhibition by 20 mM A2C was substantially reversed by an equimolar concentration of L-proline. Also, inhibition by T4C was partially reversed by L-asparagine and Lglutamine and inhibition due to A2C by L-alanine and L-glutamine. When cells were grown in high salinity media, sensitivity to inhibition by T4C increased. Conversely, A2C became ineffective as an inhibitor of cells at high salinity. Inasmuch as N. bacillaris accummulates high intracellular concentrations of free proline when grown at high salinity, the reversal of inhibition by A2C at high salinity may have been due to the high intracellular pool of proline in such cells.