The methylation of adenovirus-specific nuclear and cytoplasmic RNA

Sommer, Steve S.; Salditt-Georgieff, M; Bachenheimer, Steven L.; Darnell, James; Furuichi, Yasuhiro; Morgan, M.; Shatkin, Aaron J.

doi:10.1093/nar/3.3.749

Cited by 182 publications

(135 citation statements)

References 24 publications

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“…In an analogous fashion the average methylated dinucleotide content ('-3' peak) was found to be 1 per 330 bases for poly(A)-RNA and 1 per 420 bases for poly(A) + RNA. The material eluting at the '--4' position has been seen in a previous study (Sommer et al, 1976), and probably represents 2'-O-methylated dinucleotide from a small amount of contaminating ribosomal RNA. …”

Section: Cap and Methylated Dinucleotide Content Of Poly( A ) + And Psupporting

confidence: 63%

Characterization of Adenovirus Type 2 High Molecular Weight Nuclear Transcripts

Bachenheimer

1981

Journal of General Virology

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SUMMARYThe structure of adenovirus transcripts in the nuclei of infected cells has been studied. Evidence is presented for the existence in the steady-state population of nuclear RNA of two classes of adenovirus type 2 (Ad2)-specified large transcripts. The minor class consisted of molecules containing 3' poly(A), 5' cap structures and internal methylated nucleotides. Leader sequences at the 5' end of these large poly(A) ÷ transcripts were identified and characterized by S 1 hybridization analyses on alkaline agarose. They represented a spectrum of intermediates which ranged from completely unprocessed (5' end at 16.5) to completely condensed (5' end at 26.5) forms. S1 hybrid analyses located 3' ends of large poly(A) + nuclear RNA at 39, 50 and 61.5 on the Ad2 map. A fraction of these nuclear molecules consisted of transcripts that had undergone processing at both 3' and 5' ends of mRNA-coding regions since S1 bands corresponding to mature mRNAs for late proteins 52,55K, III, pVI and hexon, as well as 72K early protein were detected. The major class (75 to 85 %) of large nuclear transcripts was not polyadenylated, but did contain capped leader sequences. These molecules yielded discrete bands, by S 1 analysis, whose 3' termini could be positioned at sites corresponding to 5' ends of cytoplasmic mRNA (e.g. 47, 50, 51.5 and 66.5). The possible significance of these poly(A)-RNAs to the transcriptional programme of Ad2 is discussed.

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Section: Cap and Methylated Dinucleotide Content Of Poly( A ) + And Psupporting

confidence: 63%

Characterization of Adenovirus Type 2 High Molecular Weight Nuclear Transcripts

Bachenheimer

1981

Journal of General Virology

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“…Adenovirus mRNAs are methylated in the 5' two-thirds of the molecules, and m6As seem, in this system, to be conserved during mRNA processing (9,33).…”

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confidence: 83%

Precise localization of m6A in Rous sarcoma virus RNA reveals clustering of methylation sites: implications for RNA processing.

Kane¹,

Beemon²

1985

Mol. Cell. Biol.

169

306

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N6-methyladenosine (m6A) residues are present as internal base modifications in most higher eucaryotic mRNAs; however, the biological function of this modification is not known. We describe a method for localizing and quantitating m6A within a large RNA In addition to having 5'-methylated cap structures, many eucaryotic mRNAs contain internal methylated bases. N6-methyladenosine (m6A), the major form of modified nucleoside, has been detected in most higher eucaryotic cell mRNAs, in viral mRNAs, and in the virion RNA of retroviruses (2). Methylation of internal adenosines occurs in the nucleus very rapidly after synthesis of the heterogeneous nuclear RNA precursor to mRNA and before the RNA is spliced (9, 28). While the function of this internal methylation is not known, several observations suggest a significant role for m6A in RNA metabolism.Some implications for the function of internal base modifications come from methylation inhibition studies, using either cycloleucine or S-tubercidinylhomocysteine to block internal methylation of RNA. These experiments suggest an involvement of m6A in RNA processing events or in the transport of mRNA from the nucleus to the cytoplasm (6, 13, 35). It is not clear from these studies, however, that the effect of the inhibitors is directly related to the methylation state of the mRNA being examined. Secondary effects of the drugs have not been ruled out. Furthermore, the requirement for internal methylation in mRNA is not absolute, as mature messages without any detectable m6A residues do exist, including globin and histone mRNAs (24,27).In all cases characterized to date, m6A occurs only in the sequences Gm6AC and Am6AC (7,12,31,38). Preliminary localization studies with specific RNAs have determined that the distribution of m6A within a molecule is nonrandom.Rous sarcoma virus (RSV), for example, has an average of 10 to 15 m6A residues per virion RNA molecule (4, 14, 36).These methylated bases have been detected only in the 3' half of the genomic RNA (4), even though sequence analysis shows that putative methylation sites (GAC and AAC) are widely dispersed throughout the molecule (32). Likewise, internal methylation of bovine prolactin mRNA is confined to the 3' two-thirds of the message, with a high concentration of m6A in the 3' noncoding region (17). Simian virus 40 * Corresponding author.(SV40) late mRNAs, on the other hand, each contain an average of three m6As, all near the 5' ends of those messages in translated sequences (7). Adenovirus mRNAs are methylated in the 5' two-thirds of the molecules, and m6As seem, in this system, to be conserved during mRNA processing (9, 33).We have developed a method for directly identifying m6A residues within the genomic RNA of RSV. We have precisely mapped seven such sites in the genome, all within protein coding regions. In addition, we have analyzed the extent of modification at individual methylation sites. Earlier studies with SV40 (7) and with RSV (12) suggest that methylation at some specific sites is heterogeneous, with bas...

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“…RNA pppG + pppC polymeras pppG-C + Hp~ [1] [5] The availability of methylated and unmethylated mRNAs from reovirus and other viruses has facilitated studies on the role of caps in mRNA function (16)(17)(18)(19). The 5'-terminal m7G appears to be important for translation, apparently as part of a recognition mechanism for initiation complex formation (20)(21)(22)(23)(24)(25)(26)(27).…”

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confidence: 99%

Differential synthesis of blocked and unblocked 5'-termini in reovirus mRNA: effect of pyrophosphate and pyrophosphatase.

Furuichi¹,

Shatkin²

1976

Proc. Natl. Acad. Sci. U.S.A.

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Viral mRNA synthesized in vitro by reovirusassociated enzymes contained 5'-terminal ppG, GpppG, or m7GpppGm. Selective synthesis of one type of 5-end was obtained by adjusting the composition of the transcription reaction mixture based on a series of reactions proposed for formation of blocked, methylated 5'-terminal sequences of mRNA (cap formation) The presence of inorganic pyrophosphate increased the proportion of ppG 5'-ends, while addition of pyrophosphatase yielded mRNA with 5'-terminal GpppG, which in the presence of a methyl donor was converted to m7GpppGm. Many eukaryotic cellular and viral mRNAs contain blocked and methylated 5'-terminal "cap" structures of the general type, rn7G(5')ppp(5')N (1). m7G-Containing caps are also present in the high-molecular-weight, heterogeneous nuclear RNA of HeLa (2) and L cells (3), as well as in simian virus 40-specific nuclear RNA (4) and adenovirus-specific nuclear RNA which is larger than cytoplasmic viral mRNA (5). These results suggest that cap formation takes place in nuclei together with tran-

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The methylation of adenovirus-specific nuclear and cytoplasmic RNA

Cited by 182 publications

References 24 publications

Characterization of Adenovirus Type 2 High Molecular Weight Nuclear Transcripts

Characterization of Adenovirus Type 2 High Molecular Weight Nuclear Transcripts

Precise localization of m6A in Rous sarcoma virus RNA reveals clustering of methylation sites: implications for RNA processing.

Differential synthesis of blocked and unblocked 5'-termini in reovirus mRNA: effect of pyrophosphate and pyrophosphatase.

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