Comprehensive Analysis of Synonymous Codon Usage Bias for Complete Genomes and E2 Gene of Atypical Porcine Pestivirus

Intraspecific and interspecific variations in the synonymous codon usage in mitochondrial genomes of 8 pleurotus strains

In this study, we investigated the codon bias of twelve mitochondrial core protein coding genes (PCGs) in eight Pleurotus strains, two of which are from the same species. The results revealed that the codons of all Pleurotus strains had a preference for ending in A/T. Furthermore, the correlation between codon base compositions and codon adaptation index (CAI), codon bias index (CBI) and frequency of optimal codons (FOP) indices was also detected, implying the influence of base composition on codon bias. The two P. ostreatus species were found to have differences in various base bias indicators. The average effective number of codons (ENC) of mitochondrial core PCGs of Pleurotus was found to be less than 35, indicating strong codon preference of mitochondrial core PCGs of Pleurotus. The neutrality plot analysis and PR2-Bias plot analysis further suggested that natural selection plays an important role in Pleurotus codon bias. Additionally, six to ten optimal codons (ΔRSCU > 0.08 and RSCU > 1) were identified in eight Pleurotus strains, with UGU and ACU being the most widely used optimal codons in Pleurotus. Finally, based on the combined mitochondrial sequence and RSCU value, the genetic relationship between different Pleurotus strains was deduced, showing large variations between them. This research has improved our understanding of synonymous codon usage characteristics and evolution of this important fungal group.

Comparative analysis of codon usage patterns of Plasmodium helical interspersed subtelomeric (PHIST) proteins

Background

Plasmodium falciparum is a protozoan parasite that causes the most severe form of malaria in humans worldwide, which is predominantly found in sub-Saharan Africa, where it is responsible for the majority of malaria-related deaths. Plasmodium helical interspersed subtelomeric (PHIST) proteins are a family of proteins, with a conserved PHIST domain, which are typically located at the subtelomeric regions of the Plasmodium falciparum chromosomes and play crucial roles in the interaction between the parasite and its human host, such as cytoadherence, immune evasion, and host cell remodeling. However, the specific utilization of synonymous codons by PHIST proteins in Plasmodium falciparum is still unknown.

Methods

Codon usage bias (CUB) refers to the unequal usage of synonymous codons during translation, resulting in over- or underrepresentation of certain nucleotide patterns. This imbalance in CUB can impact various cellular processes, including protein expression levels and genetic variation. To investigate this, the CUB of 88 PHIST protein coding sequences (CDSs) from 5 subgroups were analyzed in this study.

Results

The results showed that both codon base composition and relative synonymous codon usage (RSCU) analysis identified a higher occurrence of AT-ended codons (AGA and UUA) in PHIST proteins of Plasmodium falciparum. The average effective number of codons (ENC) for these PHIST proteins was 36.69, indicating a weak codon preference among them, as it was greater than 35. Additionally, the correlation analysis among codon base composition (GC1, GC2, GC3, GCs), codon adaptation index (CAI), codon bias index (CBI), frequency of optimal codons (FOP), ENC, general average hydropathicity (GRAVY), aromaticity (AROMO), length of synonymous codons (L_sym), and length of amino acids (L_aa) revealed the influence of base composition and codon usage indices on codon usage bias, with GC1 having a significant impact in this study. Furthermore, the neutrality plot analysis, PR2-bias plot analysis, and ENC-GC3 plot analysis provided additional evidence that natural selection plays a crucial role in determining codon bias in PHIST proteins.

Conclusion

In conclusion, this study has enhanced our understanding of the characteristics of codon usage and genetic evolution in PHIST proteins, thereby providing data foundation for further research on antimalarial drugs or vaccines.

Genome characteristics of atypical porcine pestivirus from abortion cases in Shandong Province, China

BACKGROUND

Atypical porcine pestivirus (APPV) is a novel, highly variable porcine pestivirus. Previous reports have suggested that the virus is associated with congenital tremor (CT) type A-II in piglets, and little information is available about the correlation between the virus and sow abortion, or on coinfection with other viruses. In China, reported APPV strains were mainly isolated from South China and Central China, and data about the APPV genome from northern China are relatively scarce.

METHODS

Eleven umbilical cords, one placenta, and one aborted piglet, were collected from aborted sows of the same farm in Shandong Province of northern China. Nucleic acids were extracted from the above samples, and subsequently pooled for viral metagenomics sequencing and bioinformatics analysis. The viral coexistence status and complete genome characteristics of APPV in Shandong Province were determined.

RESULTS

In abortion cases, APPV was present with Getah virus, porcine picobirnavirus, porcine kobuvirus, porcine sapovirus, Po-Circo-like virus, porcine serum-associated circular virus, porcine bocavirus 1, porcine parvovirus 1, porcine parvovirus 3 and porcine circovirus 3, etc. The first complete genome sequence(11,556 nt) of APPV in Shandong Province of northern China, was obtained using viral metagenomics and designated APPV-SDHY-2022. Comparison with Chinese reference strains revealed that the polyprotein of APPV-SDHY-2022 shared 82.6-84.2%, 93.2-93.6%, and 80.7-85% nucleotide identity and 91.4-92.4%, 96.4-97.7%, and 90.6-92.2% amino acid identity with those of the Clade I, Clade II and Clade III strains, respectively. Phylogenetic analysis based on the complete polyprotein CDS and NS5A sequences concluded that APPV-SDHY-2022 belongs to Clade II. Analysis of the NS5A nucleotide sequences revealed homology of greater than 94.6% for the same isoform, 84.7-94.5% for different isoforms of the same clade and 76.8-81.1% for different clades. Therefore, Clade II was further divided into three subclades, and APPV-SDHY-2022 belonged to subclade 2.3. Members of Clade II have 20 unique amino acids in individual proteins, distinguishing them from Clade I and Clade III members. The E2 protein showed the greatest diversity of putative N-glycosylation sites with 9 patterns, and APPV-SDHY-2022 along with other Chinese APPV strains shared the conserved B-cell conformational epitope residues 39E, 70R, 173R, 190K and 191N of the E2 protein.

CONCLUSIONS

We reported viral coexistence and the first complete genome sequence of APPV from abortion cases and from Shandong Province. The new APPV isolate belongs to an independent branch of Clade II. Our results increase the molecular and epidemiological understanding of APPV in China.

Analysis of codon usage bias of thioredoxin in apicomplexan protozoa

BACKGROUND

Apicomplexan protozoa are a diverse group of obligate intracellular parasites causing many diseases that affect humans and animals, such as malaria, toxoplasmosis, and cryptosporidiosis. Apicomplexan protozoa possess unique thioredoxins (Trxs) that have been shown to regulate various cellular processes including metabolic redox regulation, parasite survival, and host immune evasion. However, it is still unknown how synonymous codons are used by apicomplexan protozoa Trxs.

METHODS

Codon usage bias (CUB) is the unequal usage of synonymous codons during translation which leads to the over- or underrepresentation of certain nucleotide patterns. This imbalance in CUB can impact a variety of cellular processes including protein expression levels and genetic variation. This study analyzed the CUB of 32 Trx coding sequences (CDS) from 11 apicomplexan protozoa.

RESULTS

The results showed that both codon base composition and relative synonymous codon usage (RSCU) analysis revealed that AT-ended codons were more frequently used in Cryptosporidium spp. and Plasmodium spp., while the Eimeria spp., Babesia spp., Hammondia hammondi, Neospora caninum, and Toxoplasma gondii tended to end in G/C. The average effective number of codon (ENC) value of these apicomplexan protozoa is 46.59, which is > 35, indicating a weak codon preference among apicomplexan protozoa Trxs. Furthermore, the correlation analysis among codon base composition (GC1, GC2, GC3, GCs), codon adaptation index (CAI), codon bias index (CBI), frequency of optimal codons (FOP), ENC, general average hydropathicity (GRAVY), aromaticity (AROMO), length of synonymous codons (L_sym), and length of amino acids (L_aa) indicated the influence of base composition and codon usage indices on CUB. Additionally, the neutrality plot analysis, PR2-bias plot analysis, and ENC-GC3 plot analysis further demonstrated that natural selection plays an important role in apicomplexan protozoa Trxs codon bias.

CONCLUSIONS

In conclusion, this study increased the understanding of codon usage characteristics and genetic evolution of apicomplexan protozoa Trxs, which expanded new ideas for vaccine and drug research.

Application of codon usage and context analysis in genes up- or down-regulated in neurodegeneration and cancer to combat comorbidities

Introduction

Neurodegeneration and cancer present in comorbidities with inverse effects due to the expression of genes and pathways acting in opposition. Identifying and studying the genes simultaneously up or downregulated during morbidities helps curb both ailments together.

Methods

This study examines four genes. Three of these (Amyloid Beta Precursor Protein (APP), Cyclin D1 (CCND1), and Cyclin E2 (CCNE2) are upregulated, and one protein phosphatase 2 phosphatase activator (PTPA) is simultaneously downregulated in both disorders. We investigated molecular patterns, codon usage, codon usage bias, nucleotide bias in the third codon position, preferred codons, preferred codon pairs, rare codons, and codon context.

Results

Parity analysis revealed that T is preferred over A, and G is preferred over C in the third codon position, suggesting composition plays no role in nucleotide bias in both the upregulated and downregulated gene sets and that mutational forces are stronger in upregulated gene sets than in downregulated ones. Transcript length influenced the overall %A composition and codon bias, and the codon AGG exerted the strongest influence on codon usage in both the upregulated and downregulated gene sets. Codons ending in G/C were preferred for 16 amino acids, and glutamic acid-, aspartic acid-, leucine-, valine-, and phenylalanine-initiated codon pairs were preferred in all genes. Codons CTA (Leu), GTA (Val), CAA (Gln), and CGT (Arg) were underrepresented in all examined genes.

Discussion

Using advanced gene editing tools such as CRISPR/Cas or any other gene augmentation technique, these recoded genes may be introduced into the human body to optimize gene expression levels to augment neurodegeneration and cancer therapeutic regimens simultaneously.

Analysis of synonymous codon usage patterns in mitochondrial genomes of nine Amanita species

Introduction

Codon basis is a common and complex natural phenomenon observed in many kinds of organisms.

Methods

In the present study, we analyzed the base bias of 12 mitochondrial core protein-coding genes (PCGs) shared by nine Amanita species.

Results

The results showed that the codons of all Amanita species tended to end in A/T, demonstrating the preference of mitochondrial codons of Amanita species for a preference for this codon. In addition, we detected the correlation between codon base composition and the codon adaptation index (CAI), codon bias index (CBI), and frequency of optimal codons (FOP) indices, indicating the influence of base composition on codon bias. The average effective number of codons (ENC) of mitochondrial core PCGs of Amanita is 30.81, which is <35, demonstrating the strong codon preference of mitochondrial core PCGs of Amanita. The neutrality plot analysis and PR2-Bias plot analysis further demonstrated that natural selection plays an important role in Amanita codon bias. In addition, we obtained 5–10 optimal codons (ΔRSCU > 0.08 and RSCU > 1) in nine Amanita species, and GCA and AUU were the most widely used optimal codons. Based on the combined mitochondrial sequence and RSCU value, we deduced the genetic relationship between different Amanita species and found large variations between them.

Discussion

This study promoted the understanding of synonymous codon usage characteristics and evolution of this important fungal group.

Comprehensive analysis of codon bias in 13 Ganoderma mitochondrial genomes

Introduction

Codon usage bias is a prevalent phenomenon observed across various species and genes. However, the specific attributes of codon usage in the mitochondrial genome of Ganoderma species remain unknown.

Methods

In this study, we investigated the codon bias of 12 mitochondrial core protein-coding genes (PCGs) in 9 Ganoderma species, including 13 Ganoderma strains.

Results

The codons of all Ganoderma strains showed a preference for ending in A/T. Additionally, correlations between codon base composition and the codon adaptation index (CAI), codon bias index (CBI) and frequency of optimal codons (FOP) were identified, demonstrating the impact of base composition on codon bias. Various base bias indicators were found to vary between or within Ganoderma strains, including GC3s, the CAI, the CBI, and the FOP. The results also revealed that the mitochondrial core PCGs of Ganoderma have an average effective number of codons (ENC) lower than 35, indicating strong bias toward certain codons. Evidence from neutrality plot and PR2-bias plot analysis indicates that natural selection is a major factor affecting codon bias in Ganoderma. Additionally, 11 to 22 optimal codons (ΔRSCU>0.08 and RSCU>1) were identified in 13 Ganoderma strains, with GCA, AUC, and UUC being the most widely used optimal codons in Ganoderma. By analyzing the combined mitochondrial sequences and relative synonymous codon usage (RSCU) values, the genetic relationships between or within Ganoderma strains were determined, indicating variations between them. Nevertheless, RSCU-based analysis illustrated the intra- and interspecies relationships of certain Ganoderma species.

Discussion

This study deepens our insight into the synonymous codon usage characteristics, genetics, and evolution of this important fungal group.

Study on the Characteristic Codon Usage Pattern in Porcine Epidemic Diarrhea Virus Genomes and Its Host Adaptation Phenotype

Porcine epidemic diarrhea virus (PEDV), which classified in the genus Alphacoronavirus, family Coronaviridae, is one of the most important pathogens that cause heavy economic losses in pig industry. Although intensive mutation and recombination analysis of PEDV strains were provided, systematic genome analysis were needed to elucidate the evolution mechanism and codon usage adaptation profiles of the pathogen. Here, a comprehensive investigation was carried out to reveal the systematic evolutionary processes of synonymous codon usage and host-adapted evolution phenotype of PEDV genome. We found a low codon usage bias (CUB) in PEDV genome and that nucleotide compositions, natural selection, mutation pressure and geographical diversity shapes the codon usage patterns of PEDV, with natural selection dominated the overall codon usage bias in PEDV than the others. By using the relative codon deoptimization index (RCDI) and similarity index (SiD) analysis, we observed that genotype II PEDV strains showed the highest level of adaptation phenotype to Sus scrofa than another divergent clade. To the best of our knowledge, this is the first comprehensive report elaborating the codon usage and host adaptation of PEDV. The findings offer an insight into our understanding of factors involved in PEDV evolution, adaptation and fitness toward their hosts.

Phylogenetic and codon usage analysis for replicase and capsid genes of porcine circovirus 3

Porcine circovirus type 3 (PCV3) is a highly contagious virus belonging to the family Circoviridae that causes the severe dermatitis and nephropathy syndrome. To date, PCV3 has a worldwide distribution and bring huge economic losses to swine industry. Replicase (Rep) and capsid (Cap) are two major coded proteins of PCV3. Considering the large number of new PCV3 isolates were reported in the past few years and the research for the codon usage pattern of Rep and Cap genes was still a gap, phylogenetic and codon usage analysis of these two genes was performed. Phylogenetic analyses showed that Rep genes in PCV3a were dispersed with no clear clusters while corresponding sequences in PCV3b clustered into two groups and Cap genes clustered into distinct clades according to different genotypes. Relative synonymous codon usage (RSCU) analysis revealed that the codon usage bias existed and effective number of codon (ENC) analysis showed that the bias was slight low. ENC-GC3s plot indicated that mutational pressure and other factors both played a role in PCV3 codon usage and neutrality plot analysis showed that natural selection was the main force influencing the codon usage pattern. The results presented here provided the important basic data on codon usage pattern of Rep and Cap genes, and a better understanding of the evolution and potential origin of PCV3.