Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The NH2-terminal amino acid sequence of the pp32 DNA binding protein has been determined, thus establishing its precise coding region in the polymerase gene of Rous sarcoma virus. Specific mutations were constructed in molecularly cloned Prague A DNA near the NH2- and COOH-termini of pp32 and the effects were assayed by transfection on chick embryo fibroblasts. Out-of-frame deletions at both sites and an in-frame deletion near the NH2 terminus rendered the DNA noninfectious and transformation negative. Single point mutations near the NH2 terminus reduced the transfection efficiency and the rate of virus replication. Biochemical studies indicated that the RNA-directed DNA polymerase and RNase H activities of the mutant viruses were not affected but the processing of the viral beta polypeptide was altered.
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PMID:Requirement of the avian retrovirus pp32 DNA binding protein domain for replication. 609 34

Escherichia coli ribonuclease H was purified to near-homogeneity and identified as the only additional factor required for initiation of in vitro Co1E1 DNA replication from the unique origin by RNA polymerase and DNA polymerase I. Both ribonuclease H activity and stimulating activity for Co1E1 DNA synthesis comigrate with the single protein band in gel electrophoresis. These two activities coincide throughout the process of purification. Some DNA synthesis takes place on covalently closed-circular DNA molecules other than Co1E1 DNA with the three purified enzymes. This DNA synthesis is suppressed by an Escherichia coli single-strand DNA binding protein and/or a high concentration of ribonuclease H. Negative superhelicity of template DNA is required for efficient primer formation. No evidence that supports involvement of ribonuclease III in initiation of Co1E1 DNA replication or its regulation was found.
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PMID:Purification of ribonuclease H as a factor required for initiation of in vitro Co1E1 DNA replication. 629 61

The p66/p51 human immunodeficiency virus type 1 reverse transcriptase is a heterodimer with identical N-terminal amino acid sequences. The enzyme contains two polymerization domains and one RNase H domain, which is located at the C-terminus of the p66 subunit. Both polymerization domains fold into four individual subdomains that are not arranged in a similar fashion, forming an unusually asymmetric dimer. The complexity of the RT p66/p51 heterodimer structure is simplified using solvent-accessibility surface areas to describe the buried surface area of contact among the different subdomains. In addition, the RT/DNA contacts in the recently published RT/DNA/Fab structure [Jacobo-Molina et al., Proc. Natl Acad. Sci. USA, 90, 6320-6324 (1993)] are described using the same approach. Finally, the RT/DNA complex is compared with other dimeric DNA-binding proteins. It was found that the size of the protein and the extent of the dimer interface were not directly related to the extent of contact between the protein and the DNA. Furthermore, RT, the only protein that is not a sequence-specific DNA binding protein in this analysis, had the largest surface of interaction with the nucleic acid.
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PMID:Buried surface analysis of HIV-1 reverse transcriptase p66/p51 heterodimer and its interaction with dsDNA template/primer. 753 20

We purified and characterized previously from Podospora anserina mitochondria an endonuclease, active on single-stranded, double-stranded and flap DNA, with RNAse H activity, named P49 according to the major 49 kDa band observed on SDS-PAGE. Edman sequencing allowed us to identify the corresponding gene called nuc49. Here we report the properties of the (His)-tagged NUC49 protein expressed in E. coli. We show that this protein does exhibit an endonuclease activity on plasmid DNA, circular recessed and flap M13 substrate with short protruding single strand. However, in contrast to the mt endonuclease purified fraction it does not present RNase H activity and does not cleave linear flap substrate. The activity differences between the protein expressed in E. coli and the mitochondrial endonuclease fraction previously described are discussed. NUC49 presents a strong homology with the S. pombe CDB4 curved DNA binding protein which belongs to a large family including the human cell cycle protein PA2G4 and is able to bind curved DNA. The results constitute the first description of a mitochondrial endonuclease activity associated to this family of proliferation associated homologous proteins. The function of this endonuclease either in recombination, repair or mt DNA rearrangements remains to be determined.
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PMID:Identification and biochemical analysis of a mitochondrial endonuclease of Podospora anserina related to curved-DNA binding proteins. 1718 31

Large numbers of gross chromosomal rearrangements (GCRs) are frequently observed in many cancers. High mobility group 1 (HMG1) protein is a non-histone DNA-binding protein and is highly expressed in different types of tumors. The high expression of HMG1 could alter DNA structure resulting in GCRs. Spt2p is a non-histone DNA binding protein in Saccharomyces cerevisiae and shares homology with mammalian HMG1 protein. We found that Spt2p overexpression enhances GCRs dependent on proteins for transcription elongation and polyadenylation. Excess Spt2p increases the number of cells in S phase and the amount of single-stranded DNA (ssDNA) that might be susceptible to cause DNA damage and GCR. Consistently, RNase H expression, which reduces levels of ssDNA, decreased GCRs in cells expressing high level of Spt2p. Lastly, high transcription in the chromosome V, the location at which GCR is monitored, also enhanced GCR formation. We propose a new pathway for GCR where DNA intermediates formed during transcription can lead to genomic instability.
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PMID:Spt2p defines a new transcription-dependent gross chromosomal rearrangement pathway. 1905 69