Diversity of Surface Fibril Patterns in Mimivirus Isolates

Aquino, Isabella Luiza Martins de; Serafim, Mateus Sá Magalhães; Machado, Talita Bastos; Azevedo, Bruna Luiza de; Cunha, Denilson Eduardo Silva; Ullmann, Leila Sabrina; Araújo, João Pessoa; Abrahão, Jônatas Santos

doi:10.1128/jvi.01824-22

Cited by 7 publications

(8 citation statements)

References 38 publications

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“…clusters or clumps). 40 For instance, APMV fibrils are homogeneously distributed, whereas Megavirus caiporensis appears in clumps or clusters. Both were estimated for their relative abundance of surface fibrils, whereas Megavirus caiporensis exhibited a 552-fold relative average contrast increase when compared to Borely moumouvirus, in comparison to a 394-fold increase for APMV.…”

Section: Uniqueness Of An Intriguing Structure: Diversity In Surface ...mentioning

confidence: 99%

“…Finally, more APMV-infected cells were observed (43/50), followed by Megavirus caiporensis (16/50), and Borely moumouvirus (4/50), both under the same experimental conditions. 40 These results could suggest that the pattern of fibrils may also affect adhesion and their incorporation by amoebas.…”

Section: Introductionmentioning

confidence: 97%

“…Borely moumouvirus) are morphologically similar to mimivirus M4 and present R135 and L829 genes in their genomes. 40 Interestingly, these three predicted proteins can also be found only in some GV that have fibrils when analyzing search results using the BLASTp tool 41 (Table 1) from the National Center for Biotechnology Information (NCBI). Herein, the best hits were found for all the proteins among mimiviruses from lineages A, B, and C, and for Cotonvirus japonicus , even though lineage B mimiviruses are almost fiberless.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, it is also important to highlight that the best hits were also found for R135 and L829 in viruses that do not have surface fibrils described as part of their particles, like pandoravirus and Pithovirus. 40…”

Section: Introductionmentioning

confidence: 99%

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Surface fibrils on the particles of nucleocytoviruses: A review

Aquino,

Barcelos,

Machado

et al. 2023

Exp Biol Med (Maywood)

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The capsid has a central role in viruses’ life cycle. Although one of its major functions is to protect the viral genome, the capsid may be composed of elements that, at some point, promote interaction with host cells and trigger infection. Considering the scenario of multiple origins of viruses along the viral evolution, a substantial number of capsid shapes, sizes, and symmetries have been described. In this context, capsids of giant viruses (GV) that infect protists have drawn the attention of the scientific community, especially in the last 20 years, specifically for having bacterial-like dimensions with hundreds of different proteins and exclusive features. For instance, the surface fibrils present on the mimivirus capsid are one of the most intriguing features of the known virosphere. They are 150-nm-long structures attached to a 450-nm capsid, resulting in a particle with a hairy appearance. Surface fibrils have also been described in the capsids of other nucleocytoviruses, although they may differ substantially among them. In this mini review for non-experts, we compile the most important available information on surface fibrils of nucleocytoviruses, discussing their putative functions, composition, length, organization, and origins.

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Section: Uniqueness Of An Intriguing Structure: Diversity In Surface ...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Surface fibrils on the particles of nucleocytoviruses: A review

Aquino,

Barcelos,

Machado

et al. 2023

Exp Biol Med (Maywood)

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“…At the late stage of the cycle, neo-synthesized virions bud at the periphery of the viral factory where they are filled with the genome. Finally, a glycosylated layer of fibrils composed of proteins and two large polysaccharides synthesized by the virally-encoded machinery, is added to the capsids (4, 15, 16). As a result, the 750 nm-diameter virions resemble Russian dolls made of the external layer of reticulated glycosylated fibrils (referred to as the “layer of fibrils”) decorating the surface of the icosahedral capsids.…”

Section: Introductionmentioning

confidence: 99%

Functional redundancy revealed by the deletion of the mimivirus GMC-oxidoreductase genes

Alempic

Bisio

Villalta

et al. 2023

Preprint

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The Mimivirus 1.2Mb genome is organized into a nucleocapsid-like genomic fiber composed of two closely related paralogs of GMC-oxidoreductase (1). Surprisingly, these proteins also compose the layer of fibrils that decorate the virions and are likely to play a key role in the infection (2). Each of these genes was inactivated using an original homologous recombination-based knockout protocol, with the aim of studying their essentiality by reverse genetics. None of these genes was found to be essential and each mutant could form a genomic fiber but with different stabilities. The most stable one led to the same structures as the wild type (5- and 6-start helices) and these results allowed us to propose a model explaining the coexistence of the two different helices in the virions. Furthermore, all mutants, including the double mutant, showed equivalent fitness in laboratory conditions, and the resulting virions presented the same glycosylation as the wild type, whereas the protein composition in the fibrils of the double mutant was different. Within the family, there is variability in the glycan composition of the fibril layer between clades, and even intra-clade (3, 4), and this variability now extends to the proteins composing the fibrils. These results obtained on two distinct essential processes (genome packaging and virion infectivity) illustrate the exceptional functional redundancy of the Mimiviridae, which may be the major evolutionary force behind their giant genomes.

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Functional redundancy revealed by the deletion of the mimivirus GMC-oxidoreductase genes

Alempic,

Bisio,

Villalta

et al. 2024

microLife

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The mimivirus 1.2Mb genome was shown to be organized into a nucleocapsid-like genomic fiber encased in the nucleoid compartment inside the icosahedral capsid (Villalta et al. 2022). The genomic fiber protein shell is composed of a mixture of two GMC-oxidoreductase paralogs, one of them being the main component of the glycosylated layer of fibrils at the surface of the virion (Rodrigues et al. 2015). In this study, we determined the effect of the deletion of each of the corresponding genes on the genomic fiber and the layer of surface fibrils. First, we deleted the GMC-oxidoreductase the most abundant in the genomic fiber, and determined its structure and composition in the mutant. As expected, it was composed of the second GMC-oxidoreductase and contained 5- and 6-start helices similar to the wild-type fiber. This result led us to propose a model explaining their coexistence. Then, we deleted the GMC-oxidoreductase the most abundant in the layer of fibrils to analyze its protein composition in the mutant. Second, we showed that the fitness of single mutants and the double mutant were not decreased compared to the wild-type viruses in laboratory conditions. Third, we determined that deleting the GMC-oxidoreductase genes did not impact the glycosylation or the glycan composition of the layer of surface fibrils, despite modifying their protein composition. Since the glycosylation machinery and glycan composition of members of different clades are different (Notaro et al. 2021, Notaro et al. 2022), we expanded the analysis of the protein composition of the layer of fibrils to members of the B and C clades and showed that it was different among the three clades and even among isolates within the same clade. Taken together, the results obtained on two distinct central processes (genome packaging and virion coating) illustrate an unexpected functional redundancy in members of the family Mimiviridae, suggesting this may be the major evolutionary force behind their giant genomes.

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Diversity of Surface Fibril Patterns in Mimivirus Isolates

Abstract: Mimivirus fibrils are intriguing structures that have drawn attention since their discovery. Although still under investigation, the function of fibrils may be related to host cell adhesion.

Cited by 7 publications

References 38 publications

Surface fibrils on the particles of nucleocytoviruses: A review

Surface fibrils on the particles of nucleocytoviruses: A review

Functional redundancy revealed by the deletion of the mimivirus GMC-oxidoreductase genes

Functional redundancy revealed by the deletion of the mimivirus GMC-oxidoreductase genes

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