Relationship between Poly(Adenosine 5′-diphosphate-ribose) Synthesis and Transcriptional Activity in Wheat Embryo Chromatin

Abstract

Chromatin-bound poly(adenosine 5'-diphosphate IADPI-ribose) synthetase activity was highest in ungerminated wheat ( Triticum aestivum L., cv. Mukakomugi) embryos, and it decreased after germination within 14 hours. In contrast, transcriptional activity was lowest in ungerminated wheat embryos, and it increased during germination for 24 hours or more.Histones, Hi, H2A/H2B, basic nonhistone chromosomal proteins, and acidic nonhistone chromosomal proteins (molecular weight more than 10 kilodaltons) were ADP-ribosylated in wheat germ chromatin. Specific nonhistone chromosomal protein (molecular weight of 37 kilodaltons) in seedling chromatin was not found to be ADP-ribosylated.There are many reports concerning poly(ADP-ribose) synthetase in mammalian cells (5,6,17) but only a few concerning that in plant cells (14,22). In addition to a postulated role in the cell cycle, regulation of DNA repair and replication, gene expression, differentiation, proliferation, and transformation in animal cells (1, 3, 5-7, 11, 13, 15-17, 20); poly(ADP-ribose) may be involved in chromatin condensation (2, 12). Association of poly(ADP-ribose) glycohydrolase with chromatin has been reported in animal (5, 9) and plant (10) After the addition of 5 ml of 5% (w/v) TCA, the acid-insoluble materials were collected on filter paper (Whatman, GF/C) and were washed with 5% (w/v) TCA followed by 95% (v/v) ethanol. After drying, the radioactivity was determined in toluene-based scintillation medium using a Beckman LS 100 liquid scintillation system. In one experiment, [adenylate-32P]

Structure of active chromatin: covalent modifications of histones in active and inactive genes of control and hypothyroid rat liver

“…Our results showed a much higher level of ADP-ribosylation of histones in transcriptionally inactive chromatin as compared with the active chromatin fraction. This is consistent with the suggestion of an involvement of ADP-ribosylation in transcriptional inactivation on the basis of decreased levels of ADPribosylation on germination of wheat embryos [21,22]. This does not rule out the possibility of an involvement of ADP-ribosylation in cell growth, as rapid cell growth also accompanies germination.…”

“…The validity of these conclusions will, however, depend upon the similarity of the turnover rates of these covalent modifications between active and inactive chromatin and between control and hypothyroid states. relation between ADP-ribosylation and transcriptional inactivation has also been reported [21,22].…”