The human adenovirus type 5 E1B 55kDa protein interacts with RNA promoting timely DNA replication and viral late mRNA metabolism (original) (raw)
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RNA-binding activity of the E1B 55-kilodalton protein from human adenovirus type 5
Journal of virology, 1998
The human adenovirus 5 E1B 55-kDa protein is required for efficient nucleocytoplasmic transport of late viral mRNAs. This protein is shown to have RNA-binding activity which maps to a region of the protein with homology to a family of RNA-binding proteins and which has been shown previously to be essential for functionality of the protein in vivo.
Molecular and cellular biology, 1986
The adenovirus type 5 mutant H5dl338 lacks 524 base pairs within early region 1B. The mutation removed a portion of the region encoding the related E1B-55K and -17K polypeptides but did not disturb the E1B-21K coding region. The virus can be propagated in 293 cells which contain and express the adenovirus type 5 E1A and E1B regions, but it is defective for growth in HeLa cells, in which its final yield is reduced about 100-fold compared with the wild-type virus. The mutant also fails to transform rat cells at normal efficiency. The site of the dl338 defect was studied in HeLa cells. Early gene expression and DNA replication appeared normal. Late after infection, mRNAs coded by the major late transcription unit accumulated to reduced levels. At a time when transcription rates and steady-state nuclear RNA species were normal, the rate at which late mRNA accumulated in the cytoplasm was markedly reduced. Furthermore, in contrast to the case with the wild type, transport and accumulatio...
Molecular and cellular biology, 1994
All mRNAs expressed from the adenovirus major late transcription unit have a common, 201-nucleotide-long 5' leader sequence, which consists of three short exons (the tripartite leader). This leader has two variants, either with or without the i-leader exon, which, when present, is spliced between the second and the third exons of the tripartite leader. Previous studies have shown that adenovirus early region 4 (E4) encodes two proteins, E4 open reading frame 3 (E4-ORF3) and E4-ORF6, which are required for efficient expression of mRNAs from the major late transcription unit. These two E4 proteins appear to have redundant activities, and expression of one has been shown to be sufficient for efficient major late mRNA accumulation during a lytic virus infection. In this report, we provide evidence that E4-ORF3 and E4-ORF6 both regulate major late mRNA accumulation by stimulating constitutive splicing. Moreover, we show that the two proteins have different effects on accumulation of ...
Control of adenovirus E1B mRNA synthesis by a shift in the activities of RNA splice sites
Molecular and Cellular Biology, 1984
The primary transcript from adenovirus 2 early region 1B (E1B) is processed by differential RNA splicing into two overlapping mRNAs, 13S and 22S. The 22S mRNA is the major E1B mRNA during the early phase of infection, whereas the 13S mRNA predominates during the late phase. In previous work, it has been shown that this shift in proportions of the E1B mRNAs is influenced by increased cytoplasmic stability of the 13S mRNA at late times in infection. Two observations presented here demonstrate that the increase in proportion of the 13S mRNA at late times is also regulated by a change in the specificity of RNA splicing. First, the relative concentrations of the 13S to 22S nuclear RNAs were not constant throughout infection but increased at late times. Secondly, studies with the mutant, adenovirus 2 pm2250 , provided evidence that there was an increased propensity to utilize a 5' splice in the region of the 13S 5' splice site at late times in infection. Adenovirus 2 pm2250 has a ...
Journal of virology, 1993
The E4 gene of human type C adenoviruses has been shown previously to give rise to an array of mRNAs via differential splicing. In this study, the pattern of expression of these mRNAs during lytic infection was examined, and two distinct temporal classes were defined. mRNAs of the early class were distinguished from those of the late class by the presence, in the early class, of a sequence in the 3' half of the mRNA that was removed as an intron in the late class. A single mRNA of the late class was found to show a strong dependence on the presence of the 55-kDa protein from region E1b and the open reading frame 6 protein from region E4 for its normal cytoplasmic accumulation. One feature of this mRNA that distinguishes it from other E4 mRNAs expressed at late times is the retention within it of an intron from the 5' half of E4; it may therefore be recognized as incompletely spliced by the host cell and retained in the nucleus. It is proposed that the E1b 55-kDa/E4 open read...
Journal of Virology, 2005
The human adenovirus type 5 (Ad5) E1B 55-kDa protein is required for selective nuclear export of viral late mRNAs from the nucleus and concomitant inhibition of export of cellular mRNAs in HeLa cells and some other human cell lines, but its contributions(s) to replication in normal human cells is not well understood. We have therefore examined the phenotypes exhibited by viruses carrying mutations in the E1B 55-kDa protein coding sequence in normal human fibroblast (HFFs). Ad5 replicated significantly more slowly in HFFs than it does in tumor cells, a difference that is the result of delayed entry into the late phase of infection. The A143 mutation, which specifically impaired export of viral late mRNAs from the nucleus in infected HeLa cells (R. A. Gonzalez and S. J. Flint, J. Virol. 76: 4507-4519, 2002), induced a more severe defect in viral mRNA export in HFFs. This observation indicates that the E1B 55-kDa protein regulates mRNA export during the late phase of infection of norma...
The EMBO Journal
The adenovirus type 5 early region 1B encodes a 55 kd polypeptide that functions after transcription and processing to facilitate cytoplasmic accumulation of late viral mRNAs during lytic infection. A virus, d1338, carrying a deletion within the coding region for the 55 kd product, was found to be cold-sensitive for growth. Accumulation of late viral mRNAs was more severely inhibited at 32 than at 37°C in d1338-infected cells. The metabolism of late viral transcripts was analysed within the nucleus of dl338-infected cells at 32°C. Late viral mRNAs failed to accumulate efficiently within a nuclear compartment defimed by specific RNA extraction conditions. Normally, RNA accumulated within this operationally defined compartment after leaving the nuclear matrix and before associating with the nuclear envelope. These results indicate that the 55 kd polypeptide encoded by early region 1B facilitates an intranuclear step in the metabolism of viral mRNAs, resulting in improved transport of these RNAs to the cytoplasm.
The biology of the adenovirus E1B 55K protein
FEBS Letters, 2019
The adenovirus E1B 55K (E1B) protein plays major roles in productive adenoviral infection and cellular transformation. Interest in E1B increased because of the potential of adenoviruses as therapeutic vectors, and the E1B gene is commonly deleted from adenovirus vectors for anticancer therapy. E1B activities are spatiotemporally regulated through SUMOylation and phosphorylation, and through interactions with multiple partners that occur presumably at different intracellular sites and times postinfection. E1B is implicated in the formation of viral replication compartments and regulates viral genome replication and transcription, transcriptional repression, degradation of cellular proteins, and several intranuclear steps of viral late mRNA biogenesis. Here, we review advances in our understanding of E1B during productive adenovirus replication and discuss fundamental aspects that remain unresolved.
Gene product of region E4 of adenovirus type 5 modulates accumulation of certain viral polypeptides
Journal of Virology
An adenovirus type 5 mutant, designated H5ilE4I, was constructed in which region E4 was replaced by a cloned cDNA. The cDNA was a copy of an mRNA which exclusively contains open translational reading frames 6 and 7. The phenotype of the mutant was compared with that of the previously characterized E4 mutant H2dl8O8 and wild-type adenovirus 5. Although the H5ilE4I mutant lacked at least five E4 genes, it was nondefective for growth in HeLa cells. The defects in viral DNA replication, late protein synthesis, and shutoff of host cell protein synthesis associated with the phenotype of the H2dl8O8 mutant were not observed in HeLa cells infected with the H5ilE4I mutant. However, differences were observed regarding the time of onset of viral DNA replication and the accumulation of the hexon polypeptide as well as the 72-kilodalton adenovirus-specific DNA-binding protein. The results thus indicate that open reading frame 6 or 7 or both contain all genetic information required for viral replication in tissue culture cells, whereas another E4 gene modulates the accumulation of certain viral polypeptides. The early onset of viral DNA replication in H5ilE4I-infected cells may be an indirect effect of the enhanced expression of the 72-kilodalton DNA-binding protein.
European Journal of Biochemistry, 1979
Late after infection of KB cells with adenovirus 5 an extra protein becomes associated with messenger ribonucleoprotein particles present in the polysomes. This protein has a molecular weight of 100000 and is identical to the virus-coded '100K' protein found previously. The extra protein is firmly attached to the messenger ribonucleoprotein complexes. Its binding resists exposure to high salt concentrations as used in puromycin/high-salt dissociation and equilibrium centrifugation in Cs2S04 gradients. In this respect it resembles the binding of two other proteins of M I 74000 and 48 000 which are commonly found in messenger ribonucleoprotein particles of various eukaryotic cells. The identity between the messenger ribonucleoprotein protein of MI 100000 and the '100K' protein present in the soluble part of the cytoplasm was established by sodium dodecylsulphate/ polyacrylamide gel electrophoresis, isoelectric focusing and peptide mapping after limited proteolysis with Staphylococcus aureus protease.