Cell division in a species of Erwinia IV. Metabolic blocks in panothenate biosynthesis and their relationship to inhibition of cell division.

Grula, Mary M. (Oklahoma State University, Stillwater) and E. A. Grula. Cell division in a species of Erwinia. IV. Metabolic blocks in pantothenate biosynthesis and their relationship to inhibition of cell division. J. Bacteriol. 83:989-997. 1962.-Four compounds that inhibit cell division in an Erwinia sp., d-serine, d-histidine, d-phenylalanine, and penicillin, decrease the intracellular pantothenate content of Erwinia at culture ages of 10 and 16 hr. In the case of penicillin, it appears to be the result of excessive leakage from long cells; however, with the three d-amino acids, there is a genuine inhibition of synthesis. Among agents tested that reverse the inhibition of division, only pantoyl lactone, and to a lesser extent, omega-methylpantoyl lactone, restore intracellular content of pantothenate. This restoration is considerably less effective with d-serine as a division-inhibiting agent than with the others. Other lactones, l-alpha-alanine, and ammonium chloride are ineffective, or only slightly effective, in restoring pantothenate synthesis. Effects of division-inhibiting compounds and reversing agents upon cellular coenzyme A activity in general parallel their effects on pantothenate synthesis. There is no direct correlation between ability of a compound to reverse cell-division inhibition and ability to restore synthesis of either pantothenic acid or coenzyme A. Evidence is presented that d-serine interferes with the utilization of aspartic acid and also blocks synthesis of pantoic acid. Compounds (including glucose) which tend to produce long cells result in the accumulation of pyruvic acid in the growth medium. Pantoic acid reduces, and pantoyl lactone abolishes completely, this accumulation of pyruvate. Other reversing agents do not abolish the pyruvate accumulation.