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T G Fanning

Publications and source records attributed to T G Fanning.

52 records · Page 3Linked to original sources
PubMed1981

Iodination of Escherichia coli ribosomal protein L18 abolishes its 5 S RNA binding activity.

Iodination of Escherichia coli ribosomal protein L18 inactivated the 5 S RNA binding activity of the protein. Complete activity loss occurred at a 4-fold molar excess of iodine to L18. Tyrosine was found to be the reactive amino acid. L18, prebound to 5 S RNA, was inactivated at a much slower rate than unbound L18. Treatment of L18 with tetranitromethane also resulted in an inactivation of the protein. However, much larger amounts of tetranitromethane, compared to iodine, were necessary to achieve inactivation (50% activity loss at a 600-fold molar excess of tetranitromethane to L18).

Carrier Proteins↗
PubMed1981

Topography of the C. coli 5S RNA-protein complex as determined by crosslinking with dimethyl suberimidate and dimethyl-3,3'-dithiobispropionimidate.

5S RNA-protein complexes were prepared in vitro using partially purified E. coli 5S RNA and total E. coli 70S ribosomal proteins. The complexes were isolated from sucrose gradients and shown to contain proteins L5, L18, L25 and a fourth protein not heretofore characterized and designed L31. The complexes were treated with the crosslinking reagents dimethyl suberimidate and dimethyl-3,3'-dithiobispropionimidate. Both reagents gave identical patterns of crosslinked proteins when analyzed by one-dimensional polyacrylamide/dodecylsulfate gel electrophoresis. Dimers of L5-L31', L5-L18 and L18-L18 and a trimer containing L5, L18 and L31' were identified by diagonal polyacrylamide/dodecylsulfate gel electrophoresis of the proteins crosslinked with dimethyl-3,3'-dithiobispropionimidate. No crosslinking was detected between L25 and the other three proteins.

Carrier Proteins↗
PubMed1981

Restriction endonuclease studies of hyperplastic outgrowth lines from BALB/cfC3H mouse hyperplastic mammary nodules.

The DNA's isolated from five mouse hyperplastic mammary gland outgrowth lines from BALB/cfC3H mice were digested with the restriction endonucleases PsTI, BamHI, or EcoRI; electrophoresed; and analyzed by Southern blotting and autoradiography. Proviral DNA sequences from the acquired C3H mouse mammary tumor virus were detected in the DNA of all five lines, indicating that they were infected. The DNA of the five hyperplastic lines contained more EcoRI and BamHI mouse mammary tumor virus proviral DNA fragments than did DNA from normal organs, suggesting that the hyperplastic tissues were composed of more homogeneous cell populations than was lactating mammary gland. Each hyperplastic line had unique and reproducible BamHI and EcoRI restriction (integration) patterns which were stable over as many as seven transplant generations. Three sublines, which originated from the same hyperplastic alveolar nodule, had unique integration patterns but also shared several fragments. On the basis of these observations, we propose that mouse mammary "hyperplasias" are clonal dominant premalignant neoplasms.

Animals↗
PubMed1980

Identification and partial characterization of an endogenous form of mouse mammary tumor virus that is transcribed into the virion-associated RNA genome.

Restriction mapping demonstrated the presence of several distinct proviral forms of mouse mammary tumor virus in the genome of GR mice. One of these proviruses (GR-MTV-2) was highly amplified in GR 3A cells, a cell line derived from a GR mammary tumor. By the criterion of restriction mapping, the amplified GR-MTV-2 provirus found in GR 3A cells was identical to the provirus found in M1.19 cells, a rat cell line infected with virions obtained from GR 3A culture fluid. This result clearly implies that the GR-MTV-2 provirus in GR 3A cells was transcribed into the virion-associated viral RNA genome. Cleavage of either GR 3A or M1.19 cell DNAs with the restriction enzyme Bg1 II gave rise to a 2.6 x 10(6) dalton GR-MTV-2 proviral fragment (ca. 45% of the viral genome). This fragment was isolated and mapped with thirteen restriction enzymes.

Animals↗
PubMed1980

Selective amplification of mouse mammary tumor virus in mammary tumors of GR mice.

DNAs extracted from the mammary tumors of GR mice were analyzed for mouse mammary tumor virus proviral sequences by the restriction enzyme-Southern blot procedure. The tumor DNAs contain more proviral copies of mouse mammary tumor virus than DNA from a nonmalignant tissue. The degree of proviral amplification is small (ca. one to five additional copies) and appears to be variable from tumor to tumor. The restriction patterns of the amplified proviral sequences suggest a clonal origin for the tumor mass. In addition, the restriction patterns observed after digestion with the enzymes BglII and SacI indicate that only one of the proviruses endogenous to GR mice is amplified. The amplified provirus found in GR mammary tumors is identical to the provirus that is missing in GR-Mtv-2- mice, a congenic line exhibiting a low mammary tumor incidence.

Animals↗
PubMed1980

Reevaluation of the effect of mouse mammary tumor virus infection on the BALB/c mouse hyperplastic outgrowth.

The BALB/c (C-) mouse hyperplastic outgrowth line (D1) was used to study murine mammary tumor virus (MuMTV) expression in both D1 and tumors derived from D1. D1 was transplanted into virus-infected BALB/cfC3H (C+) and virus-uninfected C- animals. In duplicate studies, tumor incidence was the same in both groups. However, the tumor latency period was longer for D1 transplanted into C+ mice (D1/C+) than for D1 transplanted into C- mice (D1/C-). MuMTV was detected in 85% of D1/C+ outgrowths and in 29% of D1/C+ tumors but was never detected in D1/C- outgrowths or tumors. D1/C- outgrowth and tumors and most of the D1/C+ tissues expressed little or no MuMTV RNA. Some D1/C+ tumors expressed substantial levels of MuMTV RNA. These same tumors also had MuMTV antigen and contained the exogenously acquired C3H-MuMTV provirus in the cellular DNA as shown by DNA fragment patterns following cleavage with Pst I and Eco RI endonucleases. D1/C+ tumors containing no viral RNA were also antigen-negative and lacked the acquired C3H provirus. These studies indicate that D1 has substantially changed in its incidence and in its response to MuMTV. MuMTV infection was not tumorigenic in the traditional sense, a finding that has led to a reevaluation of our current models of virus-host relationships and the biology of precancerous conditions.

Animals↗
PubMed1978

Evidence that proteins S1, S11 and S21 directly participates in the binding of transfer RNA to the 30S ribosome.

In a previous publication1 we reported that the tyrosine selective reagent, tetraitromethane, causes complete inactivation of E. coli 30S ribosomes for poly U directed non-enzymatic phe-tRNA binding. This inactivation was demonstrated to be due to the chemical modification of the protein moiety of the ribosome. We have no identified the proteins of the 30S particle inactivated by this modification. Using a method of ribosome reconstruction we have found that unmodified proteins S1, S11, and S21 are essential for the restoration of the phe-tRNA binding activity of tetranitromethane inactivated ribosomes. We propose that these three proteins are intimately involved in the 30S ribosome binding site for tRNA.

Bacterial Proteins↗
PubMed1976

Use of a sequence-specific DNA-binding ligand to probe the environments of EcoRI restriction endonuclease cleavage sites.

The DNAs of bacteriophage lambda and adenovirus were incubated with the sequence-specific DNA-binding ligand 6,4'-diamidino-2-phenylindole. Digestion of the ligand-DNA complexes with EcoRI nuclease and subsequent agarose gel electrophoresis demonstrated that the ligand inhibited nuclease activity at some sites, but not at others. The results suggest that diamidino-2-phynylindole can be used to probe the immediate environments of the EcoRI cleavage sites.

Adenoviridae↗
PubMed1976

Renaturation of bacteriophage lambda DNA. Determination of the optimal renaturation conditions using a single-strand-specific DNase and alkaline-sucrose-gradient assay system.

Reannealed hybrid molecules of wild-type bacteriophage lambda DNA were prepared in aqueous solutions of formamide at a variety of NaCl concentrations at both room temperature ( 22 degrees C) and 37 degrees C. Treatment of the hybrid DNA molecules with the single-strand-specific nuclease S1 from Aspergillus oryzae followed by alkaline sucrose gradient sedimentation was used to monitor the extent and fidelity of hybridization. The optimal renaturation conditions at room temperature were found to be: 50% formamide, 35-55 mM NaCl and 10 mM Tris-HCl (pH 8.5) at 20-25 mug DNA/ml. Optimal conditions at 37 degrees C were: 32% formamide, 35-55 mM NaCl and 10 mM Tris-HCl (pH 8.5) at 20-25 mug DNA/ml. Under these conditions approximately 85-90% of the input single-stranded DNA (molecular weight 1.5 X 10(7)) was rendered S1-nuclease-resistant within 8 h at room temperature and 5 h at 37 degrees C. Neither Mg2+ nor spermidine appeared to have an effect on either the extent or fidelity of duplex formation. Experiments performed with excess enzyme and with lambda/lambda imm 434 heteroduplex hybrids suggested that the hybrid that the hybrid DNA molecules formed under optimal conditions contained no, or only short (less than 1%), mismatched regions.

Binding Sites↗
PubMed1975

Iodination of Escherichia coli lac repressor. Effect of tyrosine modification on repressor activity.

Treatment of Escherichia coli lac repressor with iodine (Kl3) at 4 degrees and pH 7.5 resulted in the rapid loss of repressor DNA binding activity. At a 30-fold molar excess of iodine to repressor, inactivation was complete within 15 sec. Inducer binding under the same conditions was only slightly affected. Iodinated repressor remained tetrameric, indicating that no gross structural alteration of the protein has taken place. Control experiments demonstrated that side products of the reaction did not contribute to the observed activity loss. Moreover, no restoration of binding activity was observed when iodinated repressor was assayed under a variety of assay conditions. Incubation of repressor with lac operator containing gamma plac DNA during the iodination reaction resulted in approximately 50% protection of binding activity. This protective effect was only partially operator specific, as gammaDNA lacking the operator binding site afforded roughly 25% protection under the same conditions. Incubation with either inducer and anti-inducer molecules during the iodination reaction did not protect repressor DNA binding activity. Iodination with K-131I-3 demonstrated that at complete inactivation virtually all of the bound iodine was recovered as iodotyrosine. A minor amount of cysteine oxidation to cysteinesulfonic acid was also detected. This oxidation encompassed no more than 30% of a single cysteine residue )tentatively identified as cysteine-107). Unstable intermediate oxidation products of cysteine did not appear to be involved in the loss of DNA binding activity. Modification of amino acids other than tyrosine and cysteine was not observed. Tryptic digestion of -131I-labeled repressor suggested that approximately 90% of the incorporated radioactivity was located in the repressor N-terminal tryptic peptide. Automated sequence analysis of iodinated repressor confirmed that at roughly 0.5 bound iodine atoms per repressor subunit (corresponding to approximately 5-10% activity loss) tyrosine residues 7, 12, and 17 were labeled in the ratios 1.0:0.5:0.8. Doubling the amount of bound iodine to 1.0 atom per subunit (corresponding to approximately 50-60% activity loss) did not significantly change the pattern of incorporation.

Amino Acid Sequence↗
PubMedDate not supplied

Molecular genetic evidence of a novel morbillivirus in a long-finned pilot whale (Globicephalus melas).

A long-finned pilot whale with morbilliviral disease was stranded in New Jersey. An immunohistochemical stain demonstrated morbilliviral antigen. Reverse transcriptase-polymerase chain reaction for morbillivirus P and N genes was positive. Novel sequences most closely related to, but distinct from, those of dolphin and porpoise morbilliviruses suggest that this virus may represent a third member of the cetacean morbillivirus group.

Animals↗