Tandem Placement of a Coronavirus Promoter Results in Enhanced mRNA Synthesis from the Downstream-Most Initiation Site

Krishnan, Rajesh; Chang, Ruey-Yi; Brian, David A.

doi:10.1006/viro.1996.0210

Cited by 38 publications

(46 citation statements)

References 6 publications

(6 reference statements)

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“…These studies support a mechanism of discontinuous negative-strand synthesis reminiscent of the process of copy choice RNA recombination (39). Clearly, transcription attenuation is an attractive hypothesis which deserves serious attention, as it is consistent with the available data presented in this and other reports and represents a more direct mechanism to regulate subgenomic RNA synthesis (9,14,18,25,38). Recent UV transcription-mapping studies with mRNA transcribed from DI RNAs, however, have suggested that the subgenomic mRNAs directly originate from genome-length templates (16,24).…”

Section: Discussionsupporting

confidence: 86%

“…This model predicts that all subgenomic negative strands originate from the genomic RNA directly, rather than from mRNA. In support of this hypothesis, tandem placement of a coronavirus promoter resulted in enhanced mRNA synthesis from the downstream-most initiation sites (18). During EAV transcription, the IG element in subgenomic mRNA is derived from the IG sequences encoded in the genomic RNA during negative-strand synthesis rather than from leader sequences encoded at the 5Ј end of the genome.…”

Section: Discussionmentioning

confidence: 91%

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Subgenomic Negative-Strand RNA Function during Mouse Hepatitis Virus Infection

Baric

Yount²

2000

J Virol

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Mouse hepatitis virus (MHV)-infected cells contain full-length and subgenomic-length positive-and negative-strand RNAs. The origin and function of the subgenomic negative-strand RNAs is controversial. In this report we demonstrate that the synthesis and molar ratios of subgenomic negative strands are similar in alternative host cells, suggesting that these RNAs function as important mediators of positive-strand synthesis. Using kinetic labeling experiments, we show that the full-length and subgenomic-length replicative form RNAs rapidly accumulate and then saturate with label, suggesting that the subgenomic-length negative strands are the principal mediators of positive-strand synthesis. Using cycloheximide, which preferentially inhibits negative-strand and to a lesser extent positive-strand synthesis, we demonstrate that cycloheximide treatment equally inhibits full-length and subgenomic-length negative-strand synthesis. Importantly, following treatment, previously transcribed negative strands remain in transcriptionally active complexes even in the absence of new negative-strand synthesis. These findings indicate that the subgenomic-length negative strands are the principal templates of positive-strand synthesis during MHV infection.Mouse hepatitis virus (MHV), a coronavirus in the Nidovirales order, contains a ϳ32-kb linear, single-stranded, positivepolarity RNA genome (8,21,28). Upon entry into the cell, the viral genome is transcribed into seven to eight subgenomic mRNAs ranging in size from ϳ1.0 to 32.0 kb (21, 32). The positive-strand mRNAs are arranged in a 3Ј coterminal nested set, and each contains a 5Ј-end ϳ72-nucleotide leader RNA sequence which is derived from the 5Ј end of the genome (20, 37). Leader RNA sequences are joined to body sequences of each subgenomic-length mRNA at highly conserved intergenic (IG) sites located just upstream from the coding sequences of each viral gene (7,14,27,32). In addition to the viral mRNAs, both full-length as well as subgenomic-length negative-strand RNAs and replicative form (RF) RNAs have been detected in porcine transmissible gastroenteritis virus-, bovine coronavirus-, and MHV-infected cells (13,30,(32)(33)(34)(35). The subgenomic-length negative-strand RNAs contain antileader RNA sequences (31, 35). While MHV negative-strand RNA synthesis is rapidly inhibited by inhibitors of protein synthesis, positive-strand synthesis is significantly more resistant, suggesting that continued protein synthesis is essential for MHV negative-strand synthesis (29).Several discontinuous transcription models have been proposed to explain the presence of leader RNA sequences on positive-strand RNAs and antileader RNA sequences on fulllength and subgenomic-length negative-strand RNAs (3,10,30,31,34,35). It is generally agreed that these smaller RNAs do not originate from larger precursors (3, 15, 31). The leaderprimed transcription model proposed that a free leader RNA was synthesized from the 3Ј end of the full-length minus strand. In trans, the free leader RNA binds with highly...

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 91%

Subgenomic Negative-Strand RNA Function during Mouse Hepatitis Virus Infection

Baric

Yount²

2000

J Virol

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“…However, studies with DI RNAs containing authentic and mutated TRSs led many investigators to conclude that, beyond a minimum threshold of potential base pairing, other factors must predominate (Hiscox et al, 1995;Makino et al, 1991;van der Most et al, 1994). DI RNA studies thus provided the first indication of the importance of the local sequence context of the TRS and the position of the TRS relative to the 3 0 end of the genome (Joo and Makino, 1995;Krishnan et al, 1996;Ozdarendeli et al, 2001;van Marle et al, 1995).…”

Section: A Replication and Transcriptionmentioning

confidence: 99%

The Molecular Biology of Coronaviruses

Masters

2006

Advances in Virus Research

1,527

1,715

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Coronaviruses are large, enveloped RNA viruses of both medical and veterinary importance. Interest in this viral family has intensified in the past few years as a result of the identification of a newly emerged coronavirus as the causative agent of severe acute respiratory syndrome (SARS). At the molecular level, coronaviruses employ a variety of unusual strategies to accomplish a complex program of gene expression. Coronavirus replication entails ribosome frameshifting during genome translation, the synthesis of both genomic and multiple subgenomic RNA species, and the assembly of progeny virions by a pathway that is unique among enveloped RNA viruses. Progress in the investigation of these processes has been enhanced by the development of reverse genetic systems, an advance that was heretofore obstructed by the enormous size of the coronavirus genome. This review summarizes both classical and contemporary discoveries in the study of the molecular biology of these infectious agents, with particular emphasis on the nature and recognition of viral receptors, viral RNA synthesis, and the molecular interactions governing virion assembly.

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“…We attempted to identify putative TRSs upstream of all ORFs, both known and predicted (Tables 2 and 3). However, TRSs are not required for transcription of all coronavirus genes, because internal initiation from larger RNA transcripts is also able to facilitate translation (18,19). Certain ORFs overlap (ORFs 10 and 11, by 12 amino acids; Fig.…”

mentioning

confidence: 99%

The Genome Sequence of the SARS-Associated Coronavirus

Marra

Astell

Holt

et al. 2003

Science

1,893

1,520

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We sequenced the 29,751-base genome of the severe acute respiratory syndrome (SARS)âassociated coronavirus known as the Tor2 isolate. The genome sequence reveals that this coronavirus is only moderately related to other known coronaviruses, including two human coronaviruses, HCoV-OC43 and HCoV-229E. Phylogenetic analysis of the predicted viral proteins indicates that the virus does not closely resemble any of the three previously known groups of coronaviruses. The genome sequence will aid in the diagnosis of SARS virus infection in humans and potential animal hosts (using polymerase chain reaction and immunological tests), in the development of antivirals (including neutralizing antibodies), and in the identification of putative epitopes for vaccine development.

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Tandem Placement of a Coronavirus Promoter Results in Enhanced mRNA Synthesis from the Downstream-Most Initiation Site

Cited by 38 publications

References 6 publications

Subgenomic Negative-Strand RNA Function during Mouse Hepatitis Virus Infection

Subgenomic Negative-Strand RNA Function during Mouse Hepatitis Virus Infection

The Molecular Biology of Coronaviruses

The Genome Sequence of the SARS-Associated Coronavirus

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