Formation of the guanylylated and methylated 5′-terminus of vaccinia virus mRNA

Moss, Bernard; Gershowitz, Alan; Wei, Cha-Mer; Boone, Robert F.

doi:10.1016/0042-6822(76)90163-x

Cited by 98 publications

(57 citation statements)

References 13 publications

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“…The confronting nucleotides with only 7-methyl guanine as a methylated component, m7GS'pppA and mTGS'pppG, were not detected at any incubation time, and it was concluded that methylation at the T-position of the 5'-terminal purine nucleoside of mRNA precedes methylation of the 7-position of the blocking guanosine. This result is different from that obtained using the enzymes isolated from vaccinia virus (Moss et al, 1976) and also from the results obtained using other kinds of virus particles, which carry RNA polymerase and capping enzymes. These differences may be due to the specific organization of a series of capping enzymes and RNA polymerase in each virus particle.…”

Section: Discussioncontrasting

confidence: 54%

“…Careful investigations by incorporation of 32P-phosphate from the precursor nucleoside polyphosphates subsequently showed the number of phosphates to be three (Miura et al, 1975 a, b). Moss et al (1976) and Venkatesan et al (1980), using the enzymes solubilized from vaccinia virions, showed that cap formation was a step-wise process. In this paper, the process of cap formation has been studied using native vaccinia virus panicles under conditions similar to those in which the virus multiplies in the cell.…”

Section: Introductionmentioning

confidence: 99%

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Process of Cap Formation of Messenger RNA by Vaccinia Virus Particles Carrying an Organized Enzyme System

Urushibara

Nishimura

Miura

1981

Journal of General Virology

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SUMMARYVaccinia virus mRNAs carry the cap structure mTGS'pppAm -or mTGS'pppGm -at the 5'-terminus, which is synthesized by a series of RNA polymerase and capping enzymes contained in the virus particle. The process of the cap formation at the 5'-terminus of mRNA was studied using an in vitro system under similar conditions to those of vaccinia virus multiplication in its host cell. After adding a methyl-group donor, methyl-3H-S-adenosylmethionine, the oligonucleotides, which were the de novo synthesized 5'-terminal part of mRNA, were isolated from the RNAsynthesizing virion at appropriate time intervals, and were analysed. The 5'-5' confronting nucleotides with 2'-O-methylation, GS'pppAm and GS'pppGm, were found with the completed cap structure, mTGS'pppAm and mTG5'pppGm. The confronting nucleotides with only 7-methyl guanine as a methylated component, m7GS'pppA and mTGS'pppG, were not detected at any incubation time, and it was concluded that methylation at the T-position of the 5'-terminal purine nucleoside of mRNA precedes methylation of the 7-position of the blocking guanosine. This result is different from that obtained using the enzymes isolated from vaccinia virus (Moss et al., 1976) and also from the results obtained using other kinds of virus particles, which carry RNA polymerase and capping enzymes. These differences may be due to the specific organization of a series of capping enzymes and RNA polymerase in each virus particle.

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Section: Discussioncontrasting

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Process of Cap Formation of Messenger RNA by Vaccinia Virus Particles Carrying an Organized Enzyme System

Urushibara

Nishimura

Miura

1981

Journal of General Virology

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“…Capping occurs by a series of three enzymatic reactions in which the 5Ј triphosphate terminus of a primary transcript is first cleaved to a diphosphate-terminated RNA by RNA triphosphatase, then capped with GMP by RNA guanylyltransferase, and finally methylated at the N-7 position of guanine by RNA (guanine-7-)methyltransferase: pppN(pN) n 3 ppN(pN) n ϩ P i ppN(pN) n ϩ pppG 7 G(5Ј)pppN(pN) n ϩ PP i G(5Ј)pppN(pN) n ϩ AdoMet 3 m7 G(5Ј)pppN(pN) n ϩ AdoHcy where AdoMet is S-adenosylmethionine and AdoHcy is Sadenosylhomocysteine. This synthetic pathway was defined originally during studies of vaccinia virus and reovirus mRNA synthesis (13,31). Cellular transcripts are capped by the same series of reactions, and enzymes that catalyze these steps have been isolated from a number of cellular sources (30).…”

mentioning

confidence: 99%

Yeast mRNA Cap Methyltransferase Is a 50-Kilodalton Protein Encoded by an Essential Gene

Mao

Schwer

Shuman

1995

Molecular and Cellular Biology

104

132

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RNA (guanine-7-)methyltransferase, the enzyme responsible for methylating the 5 cap structure of eukaryotic mRNA, was isolated from extracts of Saccharomyces cerevisiae. The yeast enzyme catalyzed methyl group transfer from S-adenosyl-L-methionine to the guanosine base of capped, unmethylated poly(A). Cap methylation was stimulated by low concentrations of salt and was inhibited by S-adenosyl-L-homocysteine, a presumptive product of the reaction, but not by S-adenosyl-D-homocysteine. The methyltransferase sedimented in a glycerol gradient as a single discrete component of 3.2S. A likely candidate for the gene encoding yeast cap methyltransferase was singled out on phylogenetic grounds. The ABD1 gene, located on yeast chromosome II, encodes a 436-amino-acid (50-kDa) polypeptide that displays regional similarity to the catalytic domain of the vaccinia virus cap methyltransferase. That the ABD1 gene product is indeed RNA (guanine-7-)methyltransferase was established by expressing the ABD1 protein in bacteria, purifying the protein to homogeneity, and characterizing the cap methyltransferase activity intrinsic to recombinant ABD1. The physical and biochemical properties of recombinant ABD1 methyltransferase were indistinguishable from those of the cap methyltransferase isolated and partially purified from whole-cell yeast extracts. Our finding that the ABD1 gene is required for yeast growth provides the first genetic evidence that a cap methyltransferase (and, by inference, the cap methyl group) plays an essential role in cellular function in vivo.Eukaryotic mRNAs contain a 5Ј-terminal cap structure consisting of 7-methylguanosine linked to the 5Ј end of the transcript via a 5Ј-5Ј triphosphate bridge (3). Capping occurs by a series of three enzymatic reactions in which the 5Ј triphosphate terminus of a primary transcript is first cleaved to a diphosphate-terminated RNA by RNA triphosphatase, then capped with GMP by RNA guanylyltransferase, and finally methylated at the N-7 position of guanine by RNA (guanine-7-)methyltransferase: pppN(pN) n 3 ppN(pN) n ϩ P i ppN(pN) n ϩ pppG 7 G(5Ј)pppN(pN) n ϩ PP i G(5Ј)pppN(pN) n ϩ AdoMet 3 m7

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“…This structure is formed apparently during initiation of transcription by modification of nascent 5' ends of all cellular and most viral mRNAs (1). Capping mechanisms were first worked out in detail by studying the enzyme activities associated with human reovirus (5), vaccinia virus (12), and insect cytoplasmic polyhedrosis virus (3), eucaryotic viruses that produce capped mRNAs in vitro. Several of these activities were purified from vaccinia virions (10), and the corresponding cellular capping enzymes were subsequently isolated from HeLa (17)(18)(19) and rat liver (11) nuclei.…”

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confidence: 99%