Mechanism of stimulation of chromatin transcription by putrescine: effects on rate of elongation and number of initiation sites utilized

Abstract

As a part of a study on the mechanisms of stimulation of liver chromatin transcription by polyamines we examined the effect of putrescine on the rate of elongation of RNA chains and the number of initiation sites utilized. Techniques which permitted the separation of the bindinginitiation phase from the chain elongation stage were used. Putrescine did not change the number of sites used by E. coli RNA polymerase (ribonucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) for transcription on chromatin or DNA. The diamine caused a 40-50% stimulation of the rate of elongation per RNA chain on both chromatin and DNA.

Role of Polyamines in the Control of Cell Proliferation and Differentiation

“…Furthermore, the acetylation of arginine-rich histone fractions was reduced. Pierce and Fausto [145] have shown that putrescine may facilitate transcription on chromatin by promoting higher rates of synthesis and a more efficient use of initiation sites without causing alterations in the number of sites utilized. On the basis that acetylation of arginine-rich histones reverses their inhibitory action on RNA synthesis, and that spermidine and spermine stimulate the acetylation of these histones, it was suggested that the polyamines may play a role in the regulation of gene expression [ 1431.…”

“…The finding that MGBG inhibits E. coli RNA polymerase only at concentrations that are 1000-fold greater than those required to block the synthesis of spermidine and spermine in cultured cells [144], indicates that the inhibitory effect of MGBG on RNA synthesis is not a result of interference with this enzyme. Pierce and Fausto [145] have shown that putrescine may facilitate transcription on chromatin by promoting higher rates of synthesis and a more efficient use of initiation sites without causing alterations in the number of sites utilized.…”

Mechanism of enhanced RNA synthesis in acute-phase rat liver and its relationship to chromatin structure

“…The nuclear pellet obtained as described above was resuspended in 50mM-Tris/HCl (pH 8) and chromatin was prepared by stepwise decrease in ionic strength as described by Pierce & Fausto (1978). When chromatin was prepared for protein extraction, 0.5 mM-phenylmethanesulphonyl fluoride was included in all buffers.…”