Takeharu Kanehisa

Low molecular RNA associated with chromatin Purification and characterization of RNA that stimulates RNA synthesis

Abstract 1. Two species of RNA, 5.0 S and 4.5 S, have been purified from chick liver chromatin that stimulate specifically RNA synthesis in vitro with chromatin as template. 2. When DNA is employed as template, both RNAs are inhibitory for RNA synthesis. With chick liver chromatin as template, such stimulation is not observed with any other RNA or polyanion such as synthetic polyribonucleotide or polyvinyl sulfate. 3. Base analysis indicates that these species of RNA have a relatively higher content of uridylic acid, and available evidence suggests that 5.0-S and 4.5-S RNA are functionally unique in regulating genetic activity.

Studies on low molecular weight RNA of chromatin: Effects on template activity of chick liver chromatin

Abstract 1. 1. An RNA fraction was partially purified from chick liver chromatin. This RNA showed a sedimentation constant of 7–10 S upon sucrose density gradient analysis. 2. 2. This species of RNA inhibited the RNA synthesis in a cell-free system of Escherichia coli RNA polymerase with DNA as template, whereas with chick liver chromatin as template, the RNA synthesis was shown to be stimulated by the addition of this particular RNA. 3. 3. Preliminary analyses revealed that the RNA showed higher affinity to chromatin isolated from the same tissue, and presumably modified its structure to serve as template for RNA synthesis.

Release of template restriction in chromatin by nuclear 4.5 S RNA

The stimulatory mechanism of RNA synthesis of calf-thymus chromatin by nuclear 4.5 S RNA from the homologous tissue was investigated by using exogenously added Escherichia coli RNA polymerase. The RNA synthesis was initiated at low concentration of salt, and then the chain elongation was achieved at high concentration of ammonium sulfate in the presence of polyvinyl sulfate. Under these conditions the number of binding sites of RNA polymerase on chromatin which were capable of initiating RNA chain was increased by the addition of the 4.5 S RNA. This stimulation was presumed to result from the release of template restriction in chromatin. The polyvinyl salt minimized ribonuclease activity without changing the RNA polymerase activity bound to the template. Neither rearrangement nor release of chromatin proteins affected the amount or size of RNA produced. Preliminary analysis suggested that the molecular species of RNA produced upon the addition of the 4.5 S RNA from various tissues seemed to be heterologous.

Partial specificity of low-molecular-weight RNA that stimulates RNA synthesis in various tissues

Abstract A nuclear RNA fraction isolated from chick or calf liver, chick or calf kidney, and Rous sarcoma contains four (5.0S, 4.5S, 4.2S, 4.0S), five (5.0S, 4.5S, 4.3S, 4.2S, 4.0S), and three (5.0S, 4.2S, 4.0S) species of RNA, respectively. All RNAs except 4.2S, 4.0S, and the sarcoma 5.0S RNA are capable of stimulating significantly RNA synthesis in vitro with chromatin from the corresponding tissue as template. 5.0S RNAs from the normal tissues of the same animal are also effective in stimulating the RNA polymerization reactions with chromatin of the heterologous tissues but to lesser extent. Available evidence will show that the stimulation may presumably be due to specific structures of RNA molecules which have a high content of uridylic acid.

Ly-2.3 antigen derived from subspecies of the Asian mouse (Mus musculus castaneus)

1 Department of Cell Genetics, National Institute of Genetics, Yata 1111, Mishima, Shizuoka-ken 411, Japan 2 Graduate School of Science and Technology, Kobe University, Rokkodai, Nada, Kobe 657, Japan 3 Department of Laboratory Animal Science, The Tokyo Metropolitan Institute of Medical Science, Honkomagome, Bunkyo-ku, Tokyo 113, Japan 4 Zoology Department, University of Malaya, 59100 Kuala Lumpur, Malaysia

Interaction of chromatin components with nuclear 5.0 S RNA fraction that stimulates RNA synthesis

Chick liver nuclear 5.0 S RNA, which stimulates RNA synthesis on chromatin, binds preferentially to the deoxyribonucleoprotein in homologous chromatin. The proteins found in the isolated deoxyribonucleoprotein-5.0 S RNA complex are total amount of both H4 and H3 histone, about 20% of nonhistone protein and about 50% of both H2a and H2b histone found in the original chromatin. Cesium chloride equilibrium centrifugation of the deoxyribonucleoprotein-5.0 S RNA complex after fixation with formaldehyde shows that the 5.0 S RNA is bound to certain proteins (acid-soluble and -insoluble) in the complex. The stimulation of RNA synthesis by the nuclear RNA fraction is due to the conversion of inaccessible region of DNA to RNA polymerase into an accessible one and presumably not due to an increase in the number of binding sites for RNA polymerase in the chromatin. The release of non-histone protein from chromatin following the addition of the nuclear RNA fraction is also briefly discussed.