Wyniki wyszukiwania - Biblioteka Nauki

1

How RNA viruses exchange their genetic material

100%

Alejska M. , Kurzynska-Kokorniak A. , Broda M. , Kierzek R. , Figlerowicz M.

Acta Biochimica Polonica

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2001

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tom 48

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nr 2

EN

One of the most un usual fea tures of RNA vi ruses is their enor mous ge netic vari ability. Among the dif fer ent pro cesses con trib ut ing to the con tin u ous gen er a tion of new vi ral vari ants RNA re com bi na tion is of spe cial im por tance. This pro cess has been observed for human, animal, plant and bacterial viruses. The collected data reveal a great sus cep ti bil ity of RNA vi ruses to re com bi na tion. They also in di cate that ge netic RNA re com bi na tion (es pe cially the nonhomologous one) is a major fac tor re spon si ble for the emer gence of new vi ral strains or spe cies. Al though the for ma tion and ac cu mu la tion of vi ral recombinants was ob served in numer ous RNA vi ruses, the mo lec u lar ba sis of this phe nom e non was stud ied in only a few vi ral spe cies. Among them, brome mo saic vi rus (BMV), a model (+)RNA vi rus offers the best op por tu ni ties to in ves ti gate var i ous as pects of ge netic RNA re com bi nation in vivo. Unlike any other, the BMV-based system enables homologous and nonhomologous re com bi na tion stud ies at both the pro tein and RNA lev els. As a con sequence, BMV is the vi rus for which the struc tural re quire ments for ge netic RNA re- com bi na tion have been most pre cisely es tab lished. Nev er the less, the pre vi ously proposed model of ge netic re com bi na tion in BMV still had one weak ness: it could not really ex plain the role of RNA struc ture in nonhomologous re com bi na tion. Re cent discoveries concerning the latter problem give us a chance to fill this gap. That is why in this re view we pres ent and thor oughly dis cuss all re sults con cern ing nonhomologous recombination in BMV that have been ob tained un til now.

2

Low recombination activity of R region located at both ends of the HIV-1 genome

86%

Urbanowicz A. , Kurzyńska-Kokorniak A. , Jankowska A. , Alejska M. , Figlerowicz M.

Acta Biochimica Polonica

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2012

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tom 59

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nr 4

619-626

EN

Although two strand transfer events are indispensable for the synthesis of double-stranded DNA and establishing HIV-1 infection, the molecular basis of these phenomena is still unclear. The first obligatory template switching event occurs just at the beginning of the virus replication cycle and involves two copies of the 97-nucleotide long R region, located one each at the both ends of the HIV-1 genome (HIV-1 R). Thus, one can expect that the molecular mechanism of this process is similar to the mechanism of homologous recombination which operates in RNA viruses. To verify the above-mentioned hypothesis, we attempted to assess the recombination activity of HIV-1 R. To this end, we tested in vitro, how effectively it induces template switching by HIV-1 RT in comparison with another well-characterized sequence supporting frequent homologous crossovers in an unrelated virus (R region derived from Brome mosaic virus - BMV R). We also examined if the RNA sequences neighboring HIV-1 R influence its recombination activity. Finally, we tested if HIV-1 R could cause BMV polymerase complex to switch between RNA templates in vivo. Overall, our results have revealed a relatively low recombination activity of HIV-1 R as compared to BMV R. This observation suggests that different factors modulate the efficiency of the first obligatory strand transfer in HIV-1 and the homology-driven recombination in RNA viruses.

3

Viral genomes and their replication strategies

86%

Lisowski P. , Kleczkowski M. , Jakubczak A.

Advances in Agricultural Sciences

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2004

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tom 09

4

RNA viruses infecting fish marine – selected data

72%

Pawlikowska M. , Deptula W.

Advances in Agricultural Sciences

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2011

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tom 14

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nr 1-2

5

The left-handed double helical nucleic acids

72%

Brown B. A. , Rich A.

Acta Biochimica Polonica

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2001

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tom 48

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nr 2

EN

The conversion of right-handed dsDNA and dsRNA to the left-handed Z-con - formation in volves a re or ga ni za tion of the nu cleo tides rel a tive to each other. This con- ver sion can be fa cil i tated by the tight bind ing of a Z-conformation-specific pro tein domain from the ed it ing en zyme dsRNA adenosine deaminase. This may in flu ence the mod i fi ca tion of both pre-mRNAs as well as some replicating RNA viruses.

6

RNA recombination in brome mosaic virus, a model plus strand RNA virus

72%

Figlerowicz M. , Bujarski J. J.

Acta Biochimica Polonica

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1998

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tom 45

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nr 4

EN

Studies on the molecular mechanism of genetic recombination in RNA viruses have progressed at the time when experimental systems of efficient recombination crossovers were established. The system of brome mosaic virus (BMV) represents one of the most useful and most advanced tools for investigation of the molecular aspects of the mechanism of RNA-RNA recombination events. By using engineered BMV RNA components, the occurrence of both homologous and nonhomologous crosses were demonstrated among the segments of the BMV RNA genome. Studies show that the two types of crossovers require different RNA signal sequences and that both types depend upon the participation of BMV replicase proteins. Mutations in the two BMV-encoded replicase polypeptides (proteins 1a and 2a) reveal that their different regions participate in homologous and in nonhomologous crossovers. Based on all these data, it is most likely that homologous and nonhomologous recombinant crosses do occur via two different types of template switching events (copy-choice mechanism) where viral replicase complex changes RNA templates during viral RNA replication at distinct signal sequences. In this review we discuss various aspects of the mechanism of RNA recombination in BMV and we emphasize future projections of this research.

7

Evasion of host immune surveillance by hepatitis C virus: Potential roles in viral persistence

58%

Moorman J. P. , Joo M. , Hahn Y. S.

Archivum Immunologiae et Therapiae Experimentalis

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2001

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tom 49

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nr 3

189-194

8

New insights towards the mechanisms of replication and recombination of RNA viruses by using the brome mosaic bromovirus model system

58%

Bujarski J. J. , Dzianott A. , Urbanowicz A. , Wierzchoslawski R. , Figlerowicz M.

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nr 2 Spec.Vol.