Grula, E. A. (Oklahoma State University, Stillwater) and Mary M. Grula. Cell division in a species of Erwinia. III. Reversal of inhibition of cell division caused by d-amino acids, penicillin, and ultraviolet light. J. Bacteriol. 83:981-988. 1962.-Inhibition of cell division in an Erwinia sp. occurs in the presence of any of six d-amino acids, penicillin, or ultraviolet light. Cell-division inhibition caused by d-amino acids is pH-dependent; however, elongation caused by penicillin occurs over a wide range of pH. Bulging and spheroplast formation in the presence of penicillin occurs only at pH values below 7.6; however, division continues to be inhibited at higher pH levels. Reversal of cell-division inhibition caused by two d-amino acids (phenylalanine and histidine) can be partially overcome by their respective l-isomers. Divalent cations (Zn, Ca, Mn) cause varying amounts of reversal of division inhibition in all systems studied; each system appears to have an individual requirement. All induced division inhibitions, including that caused by penicillin, can be reversed by pantoyl lactone or omega-methylpantoyl lactone. Evidence is presented and discussed concerning the possible importance of pantoyl lactone and divalent cations in terminal steps of the cell-division process in this organism.

Amino Acids↗

PubMed1962

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.

Amino Acids↗

PubMed1962

Cell division in a species of Erwinia. V. Effect of metabolic inhibitors on terminal division and composition of a "division" medium.

Grula, E. A. (Oklahoma State University, Stillwater) and Mary M. Grula. Cell division in a species of Eriwinia. V. Effect of metabolic inhibitors on terminal division and composition of a "division" medium. J. Bacteriol. 84:492-499. 1962.-Terminal division in Erwinia spp. involves a triggering action and subsequent septum synthesis. It is a metabolic process requiring organic nitrogen and carbon and energy. The process, when triggered by pantoic acid or pantoyl lactone, is inhibited strongly by 2,4-dinitrophenol, hydroxylamine, mitomycin C, and Hg ion and to a lesser degree by cyanide, azide, 5-fluorouracil, and diisopropylfluorophosphate. Ethylenediaminetetraacetic acid completely inhibits division only when calcium ion is the triggering agent. Heating of the cells at 43 C for 10 to 20 min also completely inhibits division. Hydroxylamine, iodoacetate, and mitomycin C cause extensive lysis of growing cells. No evidence has been obtained to demonstrate the need for protein or normal ribonucleic acid synthesis in terminal division. Requirement for intact deoxyribonucleic acid (DNA) or DNA synthesis is questionable; -SH groups are not directly involved. Once triggering has occurred, septum formation appears to require synthesis of at least cell-wall mucopeptide. A "division" medium is reported and discussed.

2,4-Dinitrophenol↗

PubMed1962