In vitro, polynucleotide phosphorylase of Escherichia coli can both synthesize RNA by using nucleotide diphosphates as precursors and exonucleolytically degrade RNA in the presence of inorganic phosphate. However, because of the high in vivo concentration of inorganic phosphate in exponentially growing cells, it has been assumed that the enzyme works exclusively as an exonuclease. Here we demon...

1. Polynucleotide phosphorylase was partially purified from the inner membrane of rat liver mitochondria. 2. The partially purified particulate enzyme catalyses phosphorolysis of poly(A), poly(C), poly(U) and RNA to nucleoside diphosphates. 3. It is devoid of nucleoside diphosphate-polymerization activity. 4. Variable amounts of ADP/P(i)-exchange activity are associated with the polynucleotide ...

XRCC1 protein is required for DNA single-strand break repair and genetic stability but its biochemical role is unknown. Here, we report that XRCC1 interacts with human polynucleotide kinase in addition to its established interactions with DNA polymerase-beta and DNA ligase III. Moreover, these four proteins are coassociated in multiprotein complexes in human cell extract and together they repai...

By using N(15) as a tracer the assimilation of ammonia by the yeast, Torulopsis utilis, has been studied. It has been shown that: 1. There was no measurable incorporation of N in the protein or polynucleotide purine of carbon-starved yeast. 2. When ammonia is added to nitrogen-starved yeast there is a long lag period before division begins during which the yeast rapidly synthesizes protein, thi...

The RNA ligase and polynucleotide kinase of bacteriophage T4 are nonessential enzymes in most laboratory Escherichia coli strains. However, T4 mutants which do not induce the enzymes are severely restricted in E. coli CTr5X, a strain derived from a clinical E. coli isolate. We have mapped the restricting locus in E. coli CTr5X and have transduced it into other E. coli strains. The restrictive l...

Refinement of the diffraction data at 2.5-A resolution from orthorhombic crystals of yeast tRNAPhe has proceeded to the point where spermine and magnesium ions can be located in the difference electron density map. Two spermine molecules are found: one is located in the major groove at one end of the anticodon stem; the other is near the variable loop and curls around phosphate 10 in a region w...

Nicotinamide mononucleoside 5'-diphosphate in its reduced form is an excellent substrate for polynucleotide phosphorylase from Micrococcus luteus both in de novo polymerization reactions and in primer extension reactions. The oxidized form of the diphosphate is a much less efficient substrate; it can be used to extend primers but does not oligomerize in the absence of a primer. The cyanide addu...

Gronlund, Audrey F. (University of British Columbia, Vancouver, B.C., Canada), and J. J. R. Campbell. Enzymatic degradation of ribosomes during endogenous respiration of Pseudomonas aeruginosa. J. Bacteriol. 90:1-7. 1965.-From sedimentation analyses it was found that the ribosomal content of Pseudomonas aeruginosa decreased during endogenous respiration. A greater degree of degradation of 50S t...

The binding of estradiol--receptor complexes of mouse uterine cytosol to oligodeoxynucleotide celluloses is inhibited by the sulfonated polyaromatic dye Cibacron blue F3GA. The dye does not have any effect on the estradiol binding site. Additon of the dye to preformed estradiol--receptor--oligo(dT)-cellulose complex results in the release of estradiol--receptor. The inhibition of binding is com...

Phage phi 29 DNA cannot be phosphorylated with polynucleotide kinase and [gamma-32P]ATP because of the presence of a viral protein covalently linked to the 5' termini. The 5' ends can, however, be made susceptible to phosphorylation by treatment with alkali and alkaline phosphatase. Restriction fragments Hpa II C and Hpa II F, corresponding to the right and left ends of phi 29 DNA, respectively...