L-A virus at 3.4 Å resolution reveals particle architecture and mRNA decapping mechanism

Naitow, Hisashi; Tang, Jinghua; Canady, Mary A.; Wickner, Reed B.; Johnson, John E.

doi:10.1038/nsb844

Cited by 156 publications

(209 citation statements)

References 25 publications

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“…Guanylyltransferase also contains a trench that can adopt either open or closed conformations during the mRNA capping reaction (25,26). Furthermore, it has been noticed that secondary structure elements around the trench of Gag resemble those in guanylyltransferase (22). This enzyme forms a Gp-enzyme intermediate with GTP and transfers Gp to the diphosphorylated 5′ termini of PolII transcripts to generate a nonmethylated cap structure.…”

Section: Discussionmentioning

confidence: 99%

“…L-A transcripts are made inside the virion and presumably released to the cytoplasm through one of the pores located at the icosahedral 5-fold symmetric axes (22). The trenches are positioned in the Gag asymmetric dimer close to the 2-fold and 3-fold axes, far from the pores.…”

Section: Discussionmentioning

confidence: 99%

“…Crystallographic studies of the L-A virion have identified a trench on the outer surface of Gag that includes His154 (22,23). L-A transcripts are made inside the virion and presumably released to the cytoplasm through one of the pores located at the icosahedral 5-fold symmetric axes (22).…”

Section: Discussionmentioning

confidence: 99%

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Cap-snatching mechanism in yeast L-A double-stranded RNA virus

Fujimura

Esteban

2011

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

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The 5′ cap structure (m 7 GpppX-) is an essential feature of eukaryotic mRNA required for mRNA stability and efficient translation. Influenza virus furnishes its mRNA with this structure by a capsnatching mechanism, in which the viral polymerase cleaves host mRNA endonucleolytically 10-13 nucleotides from the 5′ end and utilizes the capped fragment as a primer to synthesize viral transcripts. Here we report a unique cap-snatching mechanism by which the yeast double-stranded RNA totivirus L-A furnishes its transcript with a cap structure derived from mRNA. Unlike influenza virus, L-A transfers only m 7 Gp from the cap donor to the 5′ end of the viral transcript, thus preserving the 5′ α-and β-phosphates of the transcript in the triphosphate linkage of the final product. This in vitro capping reaction requires His154 of the coat protein Gag, a residue essential for decapping of host mRNA and known to form m 7 Gp-His adduct. Furthermore, the synthesis of capped viral transcripts in vivo and their expression were greatly compromised by the Arg154 mutation, indicating the involvement of Gag in the cap-snatching reaction. The overall reaction and the structure around the catalytic site in Gag resemble those of guanylyltransferase, a key enzyme of cellular mRNA capping, suggesting convergent evolution. Given that Pol of L-A is confined inside the virion and unable to access host mRNA in the cytoplasm, the structural protein Gag rather than Pol catalyzing this unique cap-snatching reaction exemplifies the versatility as well as the adaptability of eukaryotic RNA viruses.transcription | Saccharomyces cerevisiae | killer toxin E ukaryotic mRNA is capped at the 5′ end by a 7-methyl GMP moiety via an inverted 5′-5′ triphosphate linkage (m 7 GpppX) (1, 2). The cap structure is required for mRNA stability and efficient translation. Capping of the RNA 5′ end is accomplished in cells and for most viruses in three sequential catalytic reactions (3, 4): removal of the 5′ γ-phosphate by RNA triphosphatase, addition of GMP from GTP by guanylyltransferase, and methylation of the added GMP by methyltransferase. Influenza virus, how-

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Cap-snatching mechanism in yeast L-A double-stranded RNA virus

Fujimura

Esteban

2011

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

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“…4 Secondary structure of capsid proteins of totiviruses. The structure of ScV-L-A CP identified in the crystal structure [29] was compared with the predicted CP structures of other eight totiviruses. The a-helix and b-strand are represented by cylinder and arrow, respectively.…”

Section: Discussionmentioning

confidence: 99%

Characterization of virus-like particles and identification of capsid proteins in Xanthophyllomyces dendrorhous

et al. 2015

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Two dsRNAs of estimated lengths of 5 (L1) and 3.7 (L2) kpb are commonly found in strains of the basidiomycetous yeast Xanthophyllomyces dendrorhous, and the presence of virus-like particles (VLPs) have been described in some strains. Recently, two putative totiviruses (XdV-L1A and XdV-L1B) were identified from L1 dsRNA and one (XdV-L2) from L2 dsRNA in the strain UCD 67-385. In some strains, there are smaller dsRNAs (0.9-1.4 kb) that probable are satellite elements. In this work, the VLPs from several strains of X. dendrorhous, which differ in their dsRNAs content, were separated by sucrose gradient and characterized in relation to the dsRNAs and proteins that compose them. It was found that all types of dsRNAs were encapsidated into VLPs, supporting the hypothesis that the smaller dsRNAs are satellite molecules. A main protein of approx. 76 or 37 kDa composed the virions that only have the L1-dsRNA or L2-dsRNA, respectively. In the strain UCD 67-385, these both proteins were identified as viral capsid protein (CP), allow to confirm the gag predicted ORFs in XdV-L1A, XdV-L1B, and XdV-L2, with CPs of 76.6, 76.2, and 38.8 kDa, respectively. Analysis of predicted structures of CPs of XdV-L1A and XdV-L1B, showed high similitudes with the CPs of ScV-L-A and other totiviruses.

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“…The hand of the resulting structure was chosen to be consistent with ScV-L-A. 40 The entire process required 70 min on a 16-processor Linux cluster, including the 8 min used to generate the starting model. Detailed statistics for the calculations (Table 1) show that, during the first three iterations, the value of the FSC never dropped below a value of 0.5 for the entire range of spatial frequencies over which the FSC was calculated.…”

Section: Image Reconstruction Example -Psv-fmentioning

confidence: 99%