Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.3 (RNase T1)
 1,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A procedure has been developed to map the genetic elements of avian tumor virus RNA, which has a molecular weight of about 3 X 10(6) daltons and a poly(A) sequence at the 3' end. For this purpose, about 30 RNase T1-resistant oligonucleotides were ordered relative to the 3'-poly(A) terminus of the RNA, to construct an oligonucleotide map of viral RNAs. A cluster of seven envelope gene (env)-specific oligonucleotides, identified by their absence from the otherwise very similar oligonucleotide map of an envelope-defective deletion mutant (which lacks the major viral glycoprotein), mapped at a distance of 0.9 to 1.6 X 10(6) daltons from the poly(A) end of sarcoma virus RNA. A cluster of three sarcoma gene (src)-specific oligonucleotides, identified by their absence from the otherwise nearly identical oligonucleotide map of a transformation-defective deletion mutant mapped at a distance of 0.2 to 0.6 X 10(6) daltons from the poly(A) end of sarcoma virus RNA. The oligonucleotide maps of sarcoma viruses and of related deletion mutants were the same from the poly(A) end up to 0.2 X 10(6) daltons and included one terminal oligonucleotide, termed C, which is found in all avian tumor viruses tested so far. Preliminary mapping experiments ordering the src-specific and env-specific oligonucleotides of recombinants, selected for sarcoma and envelope genes of different parents, agree with those obtained by comparing maps of wild type viruses and deletion mutants. A partial genetic map consistent with these results suggests that the src gene maps between the env gene and the 3'-poly(A) end of viral RNA. This map reads: poly(A)-src-env-(pol, gag).
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PMID:Sequences and functions of Rous sarcoma virus RNA. 18 29

Chicken myeloblasts transformed by avian myeloblastosis virus (AMV) in the absence of nondefective helper virus (termed nonproducer cells) were found to release a defective virus particle (DVP) that contains avian tumor viral gag proteins but lacks envelope glycoprotein and a DNA polymerase. Nonproducer cells contain a Pr76 gag precursor protein and also a protein that is indistinguishable from the Pr180 gag-pol protein of nondefective viruses. The RNA of the DVP is 7.5 kilobases (kb) long and is 0.7 kb shorter than the 8.2-kb RNAs of the helper viruses of AMV, MAV-1 and MAV-2. Comparisons based on RNA.cDNA hybridization and mapping of RNase T1-resistant oligonucleotides indicated that DVP RNA shares with MAV RNAs nearly isogenic 5'-terminal gag and pol-related sequences of 5.3 kb and a 3'-terminal c-region of 0.7 kb that is different from that found in other avian tumor viruses. Adjacent to the c-region, DVP RNA contains a contiguous specific sequence of 1.5 kb defined by 14 specific oligonucleotides. Except for two of these oligonucleotides that map at its 5' end, this sequence is unrelated to any sequences of nondefective avian tumor viruses of four different envelope subgroups as well as to the specific sequences of fibroblast-transforming avian acute leukemia and sarcoma viruses of four different RNA subgroups. The specific sequence of the DVP RNA is present in infectious stocks of AMV from this and other laboratories in an AMV-transformed myeloblast line from another laboratory, and it is about 70% related to nucleotide sequences of E26 virus, an independent isolate of an AMV-like virus. Preliminary experiments show DVP to be leukemogenic if fused into susceptible cells in the presence of helper virus. We conclude that DVP RNA is the leukemogenic component of infectious AMV and that its specific sequence, termed AMV, may carry genetic information for oncogenicity. Thus we have found here a transformation-specific RNA sequence, unrelated to helper virus, in a highly oncogenic virus that does not transform fibroblasts.
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PMID:Genetic structure of avian myeloblastosis virus, released from transformed myeloblasts as a defective virus particle. 615 39

The nucleotide sequence of an infectious molecular clone of the Akv murine leukemia virus has been determined by the dideoxy chain termination method after subcloning in bacteriophage M13 vectors. The sequence predicts an RNA genome of 8371 nucleotides containing three large open reading frames corresponding to the gag, pol, and env genes. Signal sequences for transcription, splicing, and translation have been identified. The positions of 95 major RNase T1 resistant oligonucleotides of the Akv RNA genome have been located.
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PMID:The nucleotide sequence of the Akv murine leukemia virus genome. 620 Sep 92

The 70S genomic RNA of nonleukemogenic AKR(Akv) virus was compared to that of an in vitro passaged, cloned, leukemogenic Gross A virus by fingerprint and sequence analysis. Fifty-seven of the large ribonuclease T1-resistant oligonucleotides of each virus have the same electrophoretic mobility and sequence. Thirteen large ribonuclease T1 oligo nucleotides are unique to the Gross A virus, whereas five are unique to Akv. Four of the oligonucleotides unique to each virus are related by one or two simple base changes. Five of the differences in oligonucleotides are located in the region of the genome that codes for the gag and pol genes. Eight of the differences are located near the 3' poly(A) terminus of the virus. The origins and biological consequences of these differences are discussed.
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PMID:Most sequence differences between the genomes of the Akv virus and a leukemogenic Gross A virus passaged in vitro are located near the 3' terminus. 625 22

A family of recombinant mink cell focus-forming viruses (MCF) was derived by inoculation of NFS mice with a Friend murine leukemia virus, and their genomes were analyzed by RNase T1-resistant oligonucleotide fingerprinting. The viruses were obtained from the thymuses and spleens of preleukemic and leukemic animals and were evaluated for dualtropism and oncogenicity. All these isolates induced cytopathic foci on mink cells but could be classified into two groups based on their relative infectivities for SC-1 (mouse) or mink (ATCC CCL64) cells. One group of Friend MCFs (F-MCFs) (group I) exhibited approximately equal infectivities for SC-1 and mink cells, whereas a second group (group II) infected mink cells 1,000- to 10,000-fold more efficiently than SC-1 cells. Structural analyses of the F-MCFs revealed that group I and group II viruses correlated with recombination of Friend murine leukemia virus with two distinct, but closely related, endogenous NFS proviral sequences. No correlation was found between the type of F-MCF and the tissue of origin or the disease state of the animal. Furthermore, none of the F-MCF isolates were found to be oncogenic in NFS/N or AKR/J mice. F-MCFs of both groups underwent extensive substitution of ecotropic sequences, involving much of the gag and env genes of group I F-MCFs and most of the gag, pol, and env genes of group II F-MCFs. All F-MCF isolates retained the 3' terminal U3 region of Friend murine leukemia virus. Comparison of the RNAs of the F-MCFs with RNAs of MCFs derived from NFS.Akv-1 or NFS.Akv-2 mice indicated that the F-MCFs were derived from NFS proviral sequences which are distinct from the sequences contained in NFS.Akv MCF isolates. This result suggested that recombination with particular endogenous proviral sequences to generate MCFs may be highly specific for a given murine leukemia virus.
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PMID:Generation of mink cell focus-forming viruses by Friend murine leukemia virus: recombination with specific endogenous proviral sequences. 642 51

An in vitro transcription system from Candida utilis is described. The template used is a hybrid plasmid containing Saccharomyces cerevisiae CYC1 promoter linked to a synthetic 377-bp G-minus casette (1). In vitro transcriptions are carried out in the presence of RNase. T1. Under these conditions only the transcripts that are resistant to RNase T1 accumulate. Using this protocol, it has been shown that in the absence of cytosolic factors RNA polymerase II (pol II) from C. utilis initiated RNA synthesis randomly. But both C. utilis and S. cerevisiae cell-free extracts could direct pol II from C. utilis to initiate transcription accurately. Results also indicated that the general transcription factors are functionally interchangeable between S. cerevisiae and C. utilis.
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PMID:Accurate transcription initiation by RNA polymerase II from Candida utilis. 798 59

The viral infectivity factor (Vif) protein of human immunodeficiency virus type 1 (HIV-1) is essential for viral replication in vivo. Packaging of Vif into viral particles is mediated by an interaction with viral genomic RNA and association with viral nucleoprotein complexes. Despite recent findings on the RNA-binding properties of Vif suggesting that Vif could be involved in retroviral assembly, no RNA sequence or structure specificity has been determined so far. To gain further insight into the mechanisms by which Vif might regulate viral replication, we studied the interactions of Vif with HIV-1 genomic RNA in vitro. Using extensive biochemical analysis, we have measured the affinity of recombinant Vif proteins for synthetic RNAs corresponding to various regions of the HIV-1 genome. We found that recombinant Vif proteins bind specifically to HIV-1 viral RNA fragments corresponding to the 5'-untranslated region (5'-UTR), gag and the 5' part of pol (K(d) between 45 nM and 65 nM). RNA encompassing nucleotides 1-497 or 499-996 of the HIV-1 genomic RNA bind 9+/-2 and 21+/-3 Vif molecules, respectively, and at least some of these proteins bind in a cooperative manner (Hill constant alpha(H) = 2.3). In contrast, RNAs corresponding to other parts of the HIV-1 genome or heterologous RNAs showed poor binding capacity and weak cooperativity (K(d) > 200 nM). Moreover, RNase T1 footprinting revealed a hierarchical binding of Vif, pointing to TAR and the poly(A) stem-loop structures as primary strong affinity targets, and downstream structures as secondary sites with moderate affinity. Taken together, our findings suggest that Vif may assist other proteins to maintain a correct folding of the genomic RNA in order to facilitate its packaging and further steps such as reverse transcription. Interestingly, our results suggest also that Vif could bind the viral RNA in order to protect it from the action of the antiviral factor APOBEC-3G/3F.
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PMID:Cooperative and specific binding of Vif to the 5' region of HIV-1 genomic RNA. 1623 19