Polyamine acetylation

Abstract: Geraniol and other monoterpenes found in essential oils of fruits and herbs have been suggested to represent a new class of agents for cancer chemoprevention As a first step in clarifying the mode of action of geraniol on colon carcinogenesis, we studied its effects on the growth of a human colon cancer cell line (Caco-2) Geraniol (400 microM) caused a 70% inhibition of cell growth, with cells accumulating in the S transition phase of the cell cycle, and concomitant inhibition of DNA synthesis No signs of cytotoxicity or apoptosis were detected Geraniol caused a 50% decrease of ornithine decarboxylase activity, a key enzyme of polyamine biosynthesis, which is enhanced in cancer growth This led to a 40% reduction of the intracellular pool of putrescine Geraniol also activated the intracellular catabolism of polyamines, indicated by enhanced polyamine acetylation These observations indicate that polyamine metabolism is presumably a target in the antiproliferative properties of geraniol

Abstract: Acid and base environmental stress responses were investigated in Bacillus subtilis B subtilis AG174 cultures in buffered potassium-modified Luria broth were switched from pH 85 to pH 60 and recovered growth rapidly, whereas cultures switched from pH 60 to pH 85 showed a long lag time Log-phase cultures at pH 60 survived 60 to 100% at pH 45, whereas cells grown at pH 70 survived <15% Cells grown at pH 90 survived 40 to 100% at pH 10, whereas cells grown at pH 70 survived <5% Thus, growth in a moderate acid or base induced adaptation to a more extreme acid or base, respectively Expression indices from Affymetrix chip hybridization were obtained for 4,095 protein-encoding open reading frames of B subtilis grown at external pH 6, pH 7, and pH 9 Growth at pH 6 upregulated acetoin production (alsDS), dehydrogenases (adhA, ald, fdhD, and gabD), and decarboxylases (psd and speA) Acid upregulated malate metabolism (maeN), metal export (czcDO and cadA), oxidative stress (catalase katA; OYE family namA), and the SigX extracytoplasmic stress regulon Growth at pH 9 upregulated arginine catabolism (roc), which generates organic acids, glutamate synthase (gltAB), polyamine acetylation and transport (blt), the K+/H+ antiporter (yhaTU), and cytochrome oxidoreductases (cyd, ctaACE, and qcrC) The SigH, SigL, and SigW regulons were upregulated at high pH Overall, greater genetic adaptation was seen at pH 9 than at pH 6, which may explain the lag time required for growth shift to high pH Low external pH favored dehydrogenases and decarboxylases that may consume acids and generate basic amines, whereas high external pH favored catabolism-generating acids