Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This report concerns the stable viral RNA sequences that accumulate in HEp-2 cells infected with herpes simplex virus type 1. By hybridizing labeled total DNA and restriction endonuclease DNA fragments with excess unlabeled total nuclear and cytoplasmic RNA, we determined the genetic complexity of the RNA and we mapped the regions on the physical map of herpes simplex virus type 1 DNA that are homologous to the RNA. Our results show the following. (i) The viral RNAs accumulating in the nucleus and cytoplasm of cells infected and maintained in the presence of inhibitory concentrations of either cycloheximide or emetine were homologous to 33 and 12% of viral DNA, respectively. All of the fragments tested contained sequences homologous to nuclear RNA. However, only the fragments mapping between 0.00 and 0.18, and 0.53 and 1.00 map units contained sequences homologous to cytoplasmic RNA. (ii) The viral RNAs that accumulate in the nucleus and cytoplasm of cells infected and maintained in the presence of inhibitory concentrations of phoaphonoacetic acid were homologous to 39 and 26% of viral DNA, respectively. In this instance all of the fragments except those mapping between 0.42 and 0.53 map units contained sequences homologous to cytoplasmic RNA. (iii) The viral RNAs that accumulate in the nucleus and cytoplasm 8 h after infection were homologous to greater than 50 and 41%, respectively. All of the fragments tested contained sequences homologous to cytoplasmic RNA. (iv) The viral RNAs that accumulate in the nucleus and cytoplasm of cells infected and maintained in the presence of canavanine are homologous to 33 and 19% of viral DNA, respectively. All of the fragments tested contained sequences homologous to both nuclear and cytoplasmic RNAs. Our results indicate the following. First, there are at least three phases of transcription of viral DNA. Phase 1 does not require the synthesis of host cell or viral proteins. Phase 2 requires the synthesis of viral proteins made before the initiation of viral DNA synthesis. Phase 3 appears to be related to the initiation of viral DNA synthesis. Second, both the extent of transcription and the accumulation of viral RNA in the cytoplasm are tightly regulated. The genetic complexity of total RNA accumulating in infected cells increased in each successive phase. Moreover, the genetic complexity of nuclear RNA was invariably higher than that of cytoplasmic RNA in each phase. Lastly, the results of the studies on viral RNA accumulating in canavanine-treated cells reinforce the hypothesis made previously that more than one polypeptide in each of the alpha and beta polypeptide groups is involved in the transcription preceding the transitions from alpha to beta and beta to gamma polypeptide synthesis, respectively, and that canavanine selectively inactivated subsets of these polypeptides permitting only partial transitions from alpha to beta and beta to gamma to occur.
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PMID:Regulation of herpesvirus macromolecular synthesis. VIII. The transcription program consists of three phases during which both extent of transcription and accumulation of RNA in the cytoplasm are regulated. 22 55

The puc operon of Rhodobacter sphaeroides comprises the pucBA structural genes which encode B800-850 light-harvesting beta and alpha polypeptides, respectively. Northern (RNA) blot hybridization analysis of puc operon expression has identified two pucBA-specific transcripts. The small (0.5-kilobase [kb]) transcript encodes the beta and alpha polypeptides and, under photoheterotrophic growth conditions, was approximately 200-fold more abundant than the large (2.3-kb) transcript. The 5' end of the 0.5-kb transcript was mapped at 117 nucleotides upstream from the start of pucB. The 3' ends of the 0.5-kb transcript were mapped to two adjacent nucleotides, which follow a stem-loop structure immediately 3' to the pucA stop codon. Two mutant strains, PUC705-BA and PUC-Pv, were constructed by replacement of the pucBA genes and adjacent DNA in the former case or by insertional interruption of the DNA downstream of the pucBA genes in the latter case. The two mutant strains were devoid of B800-850 complexes during photosynthetic growth but were otherwise apparently normal. The B800-850 phenotype of both PUC705-BA and PUC-Pv was not complemented in trans with a 2.5-kb PstI restriction endonuclease fragment extending from 0.75 kb upstream of pucBA to 1.3 kb downstream of pucBA, despite the presence of the 0.5-kb pucBA-specific transcript. Both of the mutant strains, however, showed restoration of B800-850 expression with a 10.5-kb EcoRI restriction endonuclease fragment in trans encompassing the 2.5-kb PstI fragment. Western immunoblot analysis revealed no B800-850-beta polypeptide as well as no polypeptide designated 15A in either mutant. Nonetheless, under photoheterotrophic growth conditions, the 0.5-kb pucBA-specific transcript was present in PUC-Pv, although no 2.3-kb transcript was detectable. We suggest that the DNA region immediately downstream of pucBA encodes a gene product(s) essential for translational or posttranslational expression of the B800-850 beta and alpha polypeptides.
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PMID:Posttranscriptional control of puc operon expression of B800-850 light-harvesting complex formation in Rhodobacter sphaeroides. 247 Jul 27

A replication-competent avian retrovirus mutant, containing a single amino acid substitution at amino acid residue 115 in the 3' endonuclease (IN) region of the polymerase (pol) gene, was characterized. DNA transfection experiments demonstrated that the mutant virus exhibited a delayed growth phenotype at 41 degrees while replicating efficiently at 35 degrees. Examination of virus-infected cells at the molecular level demonstrated that the mutant virus at either temperature was capable of synthesizing viral DNA as efficiently as wild-type Rous sarcoma virus, strain Prague A. This result suggested that the same mutation, which was also present in the IN moeity of the polymerase beta polypeptide, did not affect DNA synthesis. Further analyses demonstrated that at either temperature the mutant virus integrated its DNA at about 10-20% of wild-type level, although possibly less efficiently at 41 degrees than at 35 degrees. The mutation at residue 115 (Pro to Ser) appeared to lower the ability of IN to function in the integration of viral DNA relative to wild-type virus. No definitive conclusion could be made as to whether IN in this mutant possessed a temperature-sensitive lesion which caused the observed replication defect at 41 degrees.
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PMID:Avian retrovirus integration protein: structure-functional analysis of viable mutants. 255 39

Two deoxyoligonucleotide probes were synthesized in accordance with the available amino acid sequence of the B800-850-beta polypeptide from Rhodobacter sphaeroides and were used to isolate a 2.6-kilobase PstI fragment from R. sphaeroides 2.4.1 chromosomal DNA. Identification of the B800-850-beta and B800-850-alpha structural genes, pucB and pucA, was confirmed by DNA sequencing. Northern (RNA) blot analysis, using restriction endonuclease fragments from the cloned genes as probes, revealed a single puc-operon-specific, highly stable transcript of approximately 640 bases present in photosynthetically grown cells. In vitro transcription-translation analysis of the puc operon revealed that the maximum synthesis of the puc operon gene products was achieved when the entire 2.6-kilobase PstI fragment was used as the template, although a 537-base-pair XmaIII fragment was sufficient to direct the synthesis of pucB and pucA fusion product.
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PMID:Cloning, DNA sequence, and expression of the Rhodobacter sphaeroides light-harvesting B800-850-alpha and B800-850-beta genes. 303 82