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

A new instruction theory for antibody formation is presented. The reverse flow of information from the amino-acid sequences of small antigenic determinants to an antideterminant RNA (aRNA) seems feasible. Prerequisites are specific activating enzymes, tRNAs, ATP as well as some kind of membrane assembling the anticodons of tRNAs linearly, analogous to the linear primary structure of stretched polypeptides. Once synthesized, aRNA might be replicated, utilized as transfer factor and transcribed by means of Reverse Transcriptase into aDNA. Further steps would be the fusion of this aDNA with genetical performed DNA-molecules already coding for the basic strucures of different classes of immunoglobulins by means of a terminal deoxynucleotidyl-transferase. This could be a chromosomal or extrachromosomal integration. The second hypothesis concerns antigen-induced immunosuppression and the phenomenon of nonresponsiveness (tolerance). An overwhelming proteolysis might give rise to a degradation of antigens or receptor templates for antigenic determinants located on the surface of macrophages. On later exposure to a similar antigen proteolytic enzymes are already preformed abolishing rapidly antigenic information. The third hypothesis concerns antibody-induced immunosuppression and tolerance. Antideterminant information is integrated into the genome or established extra-chromosomally. The continuous presence of antibodies sets in motion a sequence of reactions causing an accumulation of all information intermediates including a complementary DNA strand to the aRNA. On exposure to the corresponding antigen aRNA is transcribed. However, translation might be inhibited by hybridisation with the complementary aDNA strand as well as specific RNA hydrolysis by RNase H. Concerning the immunogenity of antibodies, a proteolytical mechanism might also be possible. Taking this into account a tolerance could be suspended in the following way: 1. by influencing the overwhelming proteolytical degradation of antigenic determinants with simultaneous antigenic stimulation; 2. by substitution of aRNA to induce blocked antibody synthesis.
Infection 1975
PMID:[A new instruction theory: possibility of a reverse flow of information from polypeptide sequences to RNA particularly in antibody synthesis, and the mechanisms of tolerance induction and immunosuppression (author's transl)]. 5 2

Two forms of ribonuclease H (RNase H) have been identified both in uninfected and Herpes Simplex virus (HSV-)infected BHK cells. Identical RNase H species were detected in control- as well as in infected cells. RNase H I and II have not been found to be associated both with host cell DNA polymerase alpha and beta and HSV-induced DNA polymerase. Infection of BHK cells with HSV type 1 does not lead to a pronounced alteration of RNase H II activity but to an increase (3-fold) of the extractable RNase H I activity. RNase H I activity increases to a maximum between 8-10 hours p.i.; the bulk of HSV-DNA synthesis occurs between 6-8 hours p.i. From these experiments we draw the preliminary conclusion that RNase H I is involved in the degradation of the RNA primer which is covalently linked to newly synthesized HSV-DNA strands.
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PMID:Ribonuclease H levels in herpes simplex virus-infected cells. 625 May 16

Reverse transcriptase (RT) isolated from Rous sarcoma virus (RSV) consists of heterodimeric RTalphabeta, RTalpha, and RTbeta. The alpha subunit (63 kDa) contains an N-terminal polymerase and a C-terminal RNase H domain. The N terminus of beta (95 kDa) corresponds to alpha with the integrase domain attached to the C terminus (32 kDa). We have constructed baculoviruses expressing the genes for alpha or beta or the entire pol (99 kDa). Infection of insect cells with recombinant virus yielded highly active and soluble RSV RT enzymes that could be purified to >90% homogeneity. HPLC gel filtration showed that alpha is a dimeric enzyme that can be partially monomerized upon the addition of 45% Me(2)SO. DNA synthesis on DNA-DNA and DNA-RNA primer-templates in the presence of competitor substrates revealed that alphabeta and beta as well as alpha are processive polymerases. However, the affinity of beta and alphabeta for primer-template substrates appears to be higher than that of alpha. All RSV enzymes investigated have the potential to displace RNA-RNA duplexes more efficiently than human immunodeficiency virus type 1 RT. Unlike human immunodeficiency virus type 1 RT, RSV RTs can catalyze an initial RNase H endonucleolytic cleavage of the RNA template but not a 3' --> 5' directed processing activity.
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PMID:Soluble Rous sarcoma virus reverse transcriptases alpha, alphabeta, and beta purified from insect cells are processive DNA polymerases that lack an RNase H 3' --> 5' directed processing activity. 1047 89

Sexual transmission of HIV is the major cause of spread of HIV in Africa and the Third World and is an unmet medical need. Recently, microbicides have attracted attention because they allow females to protect themselves and their offspring. We are exploiting one of the four retroviral enzymes, the ribonuclease H, RNase H, as a novel approach for a microbicide. It is the only enzyme of HIV not yet targeted by antiretroviral therapy. The enzyme is linked to the reverse transcriptase (RT) and hydrolyzes the RNA moiety of RNA-DNA hybrids. The RNase H is located inside virus particles and normally functions during viral replication inside cells. Here we show that activating the RNase H prematurely inside the virus particles destroys the viral genome and abrogates viral infectivity. The antiviral compound consists of a synthetic oligodeoxynucleotide (ODN), which creates an artificial RNA-DNA hybrid substrate for the RNase H inside the particle. The compound was analyzed in mouse models including humanized SCID mice and the vagina of mice. Infection was reduced up to 1000-fold or could be completely prevented. The compound is suitable as microbicide or to prevent mother-to-child transmission.
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PMID:Premature activation of the HIV RNase H drives the virus into suicide: a novel microbicide? 2293 Nov 14