scholarly journals Natural Selection Plays an Important Role in Shaping the Codon Usage of Structural Genes of the Viruses Belonging to the Coronaviridae Family

Viruses ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 3
Author(s):  
Dimpal A. Nyayanit ◽  
Pragya D. Yadav ◽  
Rutuja Kharde ◽  
Sarah Cherian

Viruses belonging to the Coronaviridae family have a single-stranded positive-sense RNA with a poly-A tail. The genome has a length of ~29.9 kbps, which encodes for genes that are essential for cell survival and replication. Different evolutionary constraints constantly influence the codon usage bias (CUB) of different genes. A virus optimizes its codon usage to fit the host environment on which it savors. This study is a comprehensive analysis of the CUB for the different genes encoded by viruses of the Coronaviridae family. Different methods including relative synonymous codon usage (RSCU), an Effective number of codons (ENc), parity plot 2, and Neutrality plot, were adopted to analyze the factors responsible for the genetic evolution of the Coronaviridae family. Base composition and RSCU analyses demonstrated the presence of A-ended and U-ended codons being preferred in the 3rd codon position and are suggestive of mutational selection. The lesser ENc value for the spike ‘S’ gene suggests a higher bias in the codon usage of this gene compared to the other structural genes. Parity plot 2 and neutrality plot analyses demonstrate the role and the extent of mutational and natural selection towards the codon usage pattern. It was observed that the structural genes of the Coronaviridae family analyzed in this study were at the least under 84% influence of natural selection, implying a major role of natural selection in shaping the codon usage.

Viruses ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 991
Author(s):  
Huiguang Wu ◽  
Zhengyu Bao ◽  
Chunxiao Mou ◽  
Zhenhai Chen ◽  
Jingwen Zhao

Porcine astrovirus (PAstV), associated with mild diarrhea and neurological disease, is transmitted in pig farms worldwide. The purpose of this study is to elucidate the main factors affecting codon usage to PAstVs. Phylogenetic analysis showed that the subtype PAstV-5 sat at the bottom of phylogenetic tree, followed by PAstV-3, PAstV-1, PAstV-2, and PAstV-4, indicating that the five existing subtypes (PAstV1-PAstV5) may be formed by multiple differentiations of PAstV ancestors. A codon usage bias was found in the PAstVs-2,3,4,5 from the analyses of effective number of codons (ENC) and relative synonymous codon usage (RSCU). Nucleotides A/U are more frequently used than nucleotides C/G in the genome CDSs of the PAstVs-3,4,5. Codon usage patterns of PAstV-5 are dominated by mutation pressure and natural selection, while natural selection is the main evolutionary force that affects the codon usage pattern of PAstVs-2,3,4. The analyses of codon adaptation index (CAI), relative codon deoptimization index (RCDI), and similarity index (SiD) showed the codon usage similarities between the PAstV and animals might contribute to the broad host range and the cross-species transmission of astrovirus. Our results provide insight into understanding the PAstV evolution and codon usage patterns.


2021 ◽  
Author(s):  
Ezequiel G. Mogro ◽  
Daniela Bottero ◽  
Mauricio J. Lozano

SARS-CoV-2, the seventh coronavirus known to infect humans, can cause severe life-threatening respiratory pathologies. To better understand SARS-CoV-2 evolution, genome-wide analyses have been made, including the general characterization of its codons usage profile. Here we present a bioinformatic analysis of the evolution of SARS-CoV-2 codon usage over time using complete genomes collected since December 2019. Our results show that SARS-CoV-2 codon usage pattern is antagonistic to, and it is getting farther away from that of the human host. Further, a selection of deoptimized codons over time, which was accompanied by a decrease in both the codon adaptation index and the effective number of codons, was observed. All together, these findings suggest that SARS-CoV-2 could be evolving, at least from the perspective of the synonymous codon usage, to become less pathogenic.


Viruses ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 752 ◽  
Author(s):  
Zhen He ◽  
Haifeng Gan ◽  
Xinyan Liang

Potato virus M (PVM) is a member of the genus Carlavirus of the family Betaflexviridae and causes large economic losses of nightshade crops. Several previous studies have elucidated the population structure, evolutionary timescale and adaptive evolution of PVM. However, the synonymous codon usage pattern of PVM remains unclear. In this study, we performed comprehensive analyses of the codon usage and composition of PVM based on 152 nucleotide sequences of the coat protein (CP) gene and 125 sequences of the cysteine-rich nucleic acid binding protein (NABP) gene. We observed that the PVM CP and NABP coding sequences were GC-and AU-rich, respectively, whereas U- and G-ending codons were preferred in the PVM CP and NABP coding sequences. The lower codon usage of the PVM CP and NABP coding sequences indicated a relatively stable and conserved genomic composition. Natural selection and mutation pressure shaped the codon usage patterns of PVM, with natural selection being the most important factor. The codon adaptation index (CAI) and relative codon deoptimization index (RCDI) analysis revealed that the greatest adaption of PVM was to pepino, followed by tomato and potato. Moreover, similarity Index (SiD) analysis showed that pepino had a greater impact on PVM than tomato and potato. Our study is the first attempt to evaluate the codon usage pattern of the PVM CP and NABP genes to better understand the evolutionary changes of a carlavirus.


2013 ◽  
Vol 641-642 ◽  
pp. 675-683
Author(s):  
Xin Zhang ◽  
An Chun Cheng ◽  
Ming Shu Wang ◽  
De Kang Zhu ◽  
Xiao Jia Wang ◽  
...  

Objective: The aim was to identify the codon usage bias between the newly identified Riemerella anatipestifer (RA) major facilitator superfamily mfs_1 gene (GenBank accession No.CP003388.1) and other reference bacteriums. Methods: A comparative analysis of the codon usage bias of the 18 bacteriums was performed by using the CodonW 1.4 program and CUSP (create a codon usage table) program of EMBOSS (The European Molecular Biology Open Software Suite). Results: The results showed obvious differences of the synonymous codon usage bias in the 18 bacteriums indicated by the Codon Adaptation Index (CAI), effective number of codons (ENc), and the value of G+C content at the 3rd codon position. The codon usage pattern of the major facilitator superfamily mfs_1 gene was phylogenetically conserved and similar to that of the major facilitator superfamily mfs_1 gene of the Elizabethkingia anophelis Ag1 Contig17, with a strong bias towards the codons with A and T at the 3rd codon position. A cluster analysis of codon usage pattern of the RA major facilitator superfamily mfs_1 gene with other reference bacteriums demonstrated that the codon usage bias of the major facilitator superfamily mfs_1 genes of the 18 bacteriums had a very close relation with their gene function. The ENc-plot revealed that the genetic heterogeneity in the RA major facilitator superfamily mfs_1 gene and the 18 reference bacteriums were constrained by G+C content, while gene length exerted relatively weaker influences. In addition, comparisons of the codon preferences in the major facilitator superfamily mfs_1 gene of RA with those of Escherichia coli, yeast and humans revealed that there were 36 codons showing distinct usage differences between the RA and E. coli, and 37 between the RA and humans, but only 28 between the RA and yeast. Therefore, the yeast system may be more suitable for the expression of the RA major facilitator superfamily mfs_1 gene. Conclusion: Together, these results may improve our understanding of the evolution, pathogenesis and functional studies of RA and possibly contribute significantly to the area of other bacteriums.


BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Giovanni Franzo ◽  
Claudia Maria Tucciarone ◽  
Matteo Legnardi ◽  
Mattia Cecchinato

Abstract Background Infectious bronchitis virus (IBV) is one of the most relevant viruses affecting the poultry industry, and several studies have investigated the factors involved in its biological cycle and evolution. However, very few of those studies focused on the effect of genome composition and the codon bias of different IBV proteins, despite the remarkable increase in available complete genomes. In the present study, all IBV complete genomes were downloaded (n = 383), and several statistics representative of genome composition and codon bias were calculated for each protein-coding sequence, including but not limited to, the nucleotide odds ratio, relative synonymous codon usage and effective number of codons. Additionally, viral codon usage was compared to host codon usage based on a collection of highly expressed genes in IBV target and nontarget tissues. Results The results obtained demonstrated a significant difference among structural, non-structural and accessory proteins, especially regarding dinucleotide composition, which appears under strong selective forces. In particular, some dinucleotide pairs, such as CpG, a probable target of the host innate immune response, are underrepresented in genes coding for pp1a, pp1ab, S and N. Although genome composition and dinucleotide bias appear to affect codon usage, additional selective forces may act directly on codon bias. Variability in relative synonymous codon usage and effective number of codons was found for different proteins, with structural proteins and polyproteins being more adapted to the codon bias of host target tissues. In contrast, accessory proteins had a more biased codon usage (i.e., lower number of preferred codons), which might contribute to the regulation of their expression level and timing throughout the cell cycle. Conclusions The present study confirms the existence of selective forces acting directly on the genome and not only indirectly through phenotype selection. This evidence might help understanding IBV biology and in developing attenuated strains without affecting the protein phenotype and therefore immunogenicity.


2011 ◽  
Vol 57 (12) ◽  
pp. 1016-1023 ◽  
Author(s):  
Xue Lian Luo ◽  
Jian Guo Xu ◽  
Chang Yun Ye

In this study, we analysed synonymous codon usage in Shigella flexneri 2a strain 301 (Sf301) and performed a comparative analysis of synonymous codon usage patterns in Sf301 and other strains of Shigella and Escherichia coli . Although there was a significant variety in codon usage bias among different Sf301 genes, there was a slight but observable codon usage bias that could primarily be attributable to mutational pressure and translational selection. In addition, the relative abundance of dinucleotides in Sf301 was observed to be independent of the overall base composition but was still caused by differential mutational pressure; this also shaped codon usage. By comparing the relative synonymous codon usage values across different Shigella and E. coli strains, we suggested that the synonymous codon usage pattern in the Shigella genomes was strain specific. This study represents a comprehensive analysis of Shigella codon usage patterns and provides a basic understanding of the mechanisms underlying codon usage bias.


2021 ◽  
Author(s):  
Alexander L Cope ◽  
Premal Shah

Patterns of non-uniform usage of synonymous codons (codon bias) varies across genes in an organism and across species from all domains of life. The bias in codon usage is due to a combination of both non-adaptive (e.g. mutation biases) and adaptive (e.g. natural selection for translation efficiency/accuracy) evolutionary forces. Most population genetics models quantify the effects of mutation bias and selection on shaping codon usage patterns assuming a uniform mutation bias across the genome. However, mutation biases can vary both along and across chromosomes due to processes such as biased gene conversion, potentially obfuscating signals of translational selection. Moreover, estimates of variation in genomic mutation biases are often lacking for non-model organisms. Here, we combine an unsupervised learning method with a population genetics model of synonymous codon bias evolution to assess the impact of intragenomic variation in mutation bias on the strength and direction of natural selection on synonymous codon usage across 49 Saccharomycotina budding yeasts. We find that in the absence of a priori information, unsupervised learning approaches can be used to identify regions evolving under different mutation biases. We find that the impact of intragenomic variation in mutation bias varies widely, even among closely-related species. We show that the overall strength and direction of selection on codon usage can be underestimated by failing to account for intragenomic variation in mutation biases. Interestingly, genes falling into clusters identified by machine learning are also often physically clustered across chromosomes, consistent with processes such as biased gene conversion. Our results indicate the need for more nuanced models of sequence evolution that systematically incorporate the effects of variable mutation biases on codon frequencies.


2021 ◽  
Author(s):  
Yanan Fu ◽  
Yanping Huang ◽  
Jingjing Rao ◽  
Feng Zeng ◽  
Ruiping Yang ◽  
...  

Abstract The outbreak of COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, spread across hosts from humans to animals, transmitting particularly effectively in mink. How SARS-CoV-2 selects and evolves in the host, and the differences in the evolution of different animals are still unclear. To analysis the mutation and codon usage bias of SARS-CoV-2 in infected humans and animals. The SARS-CoV-2 sequence in mink (Mink-SARS2) and binding energy with receptor were calculated compared with human. The relative synonymous codon usage of viral encoded gene was analyzed to characterize the differences and the evolutionary characteristics. A synonymous codon usage analysis showed that SARS-CoV-2 is optimized to adapt in the animals in which it is currently reported, and all of the animals showed decreased adaptability relative to that of humans, except for mink. The neutrality plot showed that the effect of natural selection on different SARS-CoV-2 sequences is stronger than mutation pressure. A binding affinity analysis indicated that the spike protein of the SARS-CoV-2 variant in mink showed a greater preference for binding with the mink receptor ACE2 than with the human receptor, especially as the mutation Y453F and N501T in Mink-SARS2 lead to improvement of binding affinity for mink receptor. In summary, mutations Y453F and N501T in Mink-SARS2 lead to improvement of binding affinity with mink receptor, indicating possible natural selection and current host adaptation. Monitoring the variation and codon bias of SARS-CoV-2 provides a theoretical basis for tracing the epidemic, evolution and cross-species spread of SARS-CoV-2.


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