Search Results (124)

The synthesis of various heterocyclic base modifications of nucleic acids has been thoroughly investigated; however, much less is known about their catabolism. Also, little is known about the transport of such compounds across the microbial cell membranes. Using the Saccharomyces cerevisiae single-gene deletion library, we performed genome-wide screening for genes affecting the growth of yeast in minimal media supplemented with N⁴-acetylcytosine as a source of uracil. We found that Fcy1, Fcy21, Bud16, Gnd1, and Fur4 proteins are required for efficient growth in the tested medium. Additionally, we used several heterocyclic pyrimidine bases and Fcy homolog mutants to test their growth in respective minimal media. We found that tested permeases differently affect the growth of yeast that is dependent on the heterocyclic pyrimidine bases used as a source of uracil. The most pronounced effect was observed for the ∆fur4 mutant, which was growing much slower than the corresponding wild-type strain in the media supplemented with N⁴-acetylcytosine, 4-methylthiouracil, N⁴-methylcytosine, N⁴,N⁴-dimethylcytosine, 2-thiouracil, or 4-thiouracil. We suggest that Fur4 protein is the major yeast transporter of modified heterocyclic pyrimidine bases. Our observations might be helpful when investigating the actions of various heterocyclic base-based antifungal, anticancer, and antiviral drugs. Full article

Global climate change is leading to more frequent extreme cold events, underscoring the need to study citrus cold tolerance to support breeding and enable potential northward expansion of citrus cultivation. In this study, the ‘Miyagawa’ wild type and its cold-tolerant mutant were selected for systematic comparison across cold-resistant phenotypes, leaf tissue structure, physiological and biochemical characteristics, and Cor8 gene expression. The mutant exhibited 50% lower relative conductivity and malondialdehyde (MDA) content under −6 °C stress compared to the wild type, indicating reduced membrane damage. Antioxidant enzyme activities were significantly higher in the mutant: superoxide dismutase (SOD) activity increased by 10–30%, peroxidase (POD) by 28%, and catalase (CAT) by up to 2-fold. Proline content was 57% higher in the mutant at peak levels, supporting stronger osmotic regulation. Moreover, Cor8 gene expression in the mutant was up to 2.98 times higher than in the wild type during natural overwintering. These findings confirm that the ‘Miyagawa’ mutant possesses distinct physiological, anatomical, and molecular advantages for low-temperature adaptation and provides valuable germplasm for breeding cold-tolerant citrus varieties. Full article

Understanding the molecular regulation of citric acid accumulation in citrus fruits is crucial, as acidity directly influences fruit flavor, consumer preference, and commercial value. Citric acid is the predominant organic acid in citrus, and its levels are shaped by several factors, including genetic and developmental factors. ‘Jinyan’ Bingtang orange (Citrus sinensis cv. Jinyan) is a novel mutant derived from ‘Jinhong’ Bingtang orange (C. sinensis cv. Jinhong) that has a noticeably sour taste. However, the molecular basis of the increased citrate content in ‘Jinyan’ fruits remains unclear. This study compared the organic acid profiles and expression of citric acid metabolism-related genes between ‘Jinyan’ and ‘Jinhong’ fruit juice sacs throughout fruit development. The trend of citric acid content in both cultivars was similar; however, ‘Jinyan’ consistently presented significantly higher levels than ‘Jinhong’ did from 95 to 215 days after flowering (DAF). After 155 DAF, the transcript levels of citrate biosynthesis-related genes (PEPC1, PEPC2, PEPC3, CS1, and CS2) and citrate transport-related genes (V₁-E1, V₁-E2, V₀-a2, V₀-d, VHP1, VHP2, and CsPH8) were significantly greater in ‘Jinyan’ than in ‘Jinhong’. In contrast, citrate degradation-related genes (NAD-IDH2 and NAD-IDH3) were expressed at lower levels than in ‘Jinhong’. Notably, the expression patterns of V₁-E2 and CsPH8 closely matched the changes in citrate content in both cultivars. These results indicate that, compared with ‘Jinhong’, high citric acid accumulation in the juice sacs of ‘Jinyan’ fruit is likely due to increased citrate synthesis (via upregulated PEPCs and CSs) and increased vacuolar citrate sequestration (via upregulated proton pumps and transporters), coupled with reduced citrate degradation (lower NAD-IDH2/3). Full article

Background/Objectives: N-Myristoyltransferase inhibitors (NMTi) represent a novel antiviral strategy against mammarenaviruses such as Lassa and Junin viruses. The Z matrix protein inhibits viral ribonucleoprotein (vRNP) activity in a dose-dependent manner. Here, we investigated whether Z-mediated vRNP inhibition depends on Z myristoylation or oligomerization. Methods: We used HEK293T cells transfected with wild-type (WT) or G2A-mutated Z constructs in LCMV minigenome (MG) assays. Cells were treated with the NMTi IMP-1088 and the proteasome inhibitor MG132. Z protein expression, vRNP activity, and VLP production were analyzed by immunofluorescence, western blotting, and colocalization analyses. Results: IMP-1088 treatment led to proteasome-mediated degradation of Z, reducing its inhibition of vRNP activity, which was restored by MG132. The non-myristoylated Z G2A mutant retained vRNP inhibitory activity but showed impaired oligomerization and budding capacity. These findings demonstrate that Z-mediated vRNP inhibition is independent of myristoylation and oligomerization. Conclusions: Z myristoylation and oligomerization are not required for its inhibitory vRNP activity. Targeting Z myristoylation with NMTi impairs virus assembly and budding without affecting Z-mediated inhibition of vRNP activity, supporting the development of NMTi as a promising broad-spectrum antiviral strategy against mammarenaviruses. Full article

The budding yeast Saccharomyces cerevisiae is a widely utilized model system with myriad applications in terms of industrial, biotechnology, and synthetic biology purposes. One such application is the biosynthesis of commercially and medically important bioactive compounds and their precursors, which oftentimes require culturing conditions at low temperatures to optimize production yield rather than cellular fitness. To lend insight into genetic modifications that may assist this goal, this work focuses on a systematic analysis of the genes that result in an increase in survival following freezing. At present, these genes have been identified in a wide variety of S. cerevisiae wild-type backgrounds—that vary significantly in their properties and behaviors—and in the conditions that led to the annotation of the freeze–thaw survival phenotype. In this work, we report a complete characterization of the thermal tolerance and viability for the freeze–thaw gene family following a standardized protocol within a unified genetic background, the extensively used BY4741 laboratory strain. Our results reveal that five out of these six genes are linked to increased viability in response to both freeze–thaw stress as well as enhanced survival during a heat shock stressor. Follow-up analysis characterized the local spatial effects that gene modification at each locus causes when utilizing the common kanamycin resistance cassette (KanMX6) for the creation of mutant strains and engineering purposes. Full article

The trade-off between growth and defense is common in plants. We previously demonstrated that BnaA03.WRKY28 weakened resistance strength but promoted shoot branching in Brassica napus (rapeseed). However, the molecular mechanism by which WRKY28 promotes branching formation is still obscure. In this study, we found that BnaA01.BRC1, BnaC01.BRC1, and BnaC03.BRC1 are mainly expressed in the leaf axils and contained W-box cis-acting elements in the promoter regions. BnaA03.WRKY28 directly bound to the promoter regions of these three copies and inhibited their expression. The brc1 mutants, the BnaA01.BRC1, BnaC01.BRC1 BnaA03.BRC1 and BnaC03.BRC1 were simultaneously knocked out, mediated by CRISPR/Cas9, and exhibited excessive branching. The expression level of the ABA biosynthesis encoding gene NCED3 was significantly reduced in the mutant compared to that in the WT. Instead, the expression level of the ABA catabolism encoding gene CYP707A3 was significantly higher than that in WT. These results suggest that the excessive branching of the brc1 mutant may be caused by the release of ABA-mediated bud dormancy. This study provides direct evidence for the potential mechanism of the WRKY28-BRC1 transcription factor module contributing to shoot branching in rapeseed. Full article

Flower color serves as a vital ornamental feature of landscape plants; Sophora japonica L. mutant ‘AM’ exhibits the different colors from the common S. japonica. ‘AM’, presenting with a light purple-red wing and keel and yellowish-white flag petals, while common S. japonica is yellow and white. The metabolites contributing to this color specificity in red-flowered S. japonica ‘AM’ are not yet fully understood. In this study, the flag, wing, and keel petals were collected from ‘AM’ at various phases, including the flower bud phase, initial flowering phase, full bloom phase, and final flowering phase, for conducting the metabolic assays targeting anthocyanins. Subsequently, we identified 45 anthocyanin-related metabolites, including nine flavonoids and 36 anthocyanins. Ten major floral chromoside metabolites were found to affect the coloration differences among the petals, where the most abundant anthocyanin was cyanidin-3-O-glucoside (Cy3G), which was much higher in the keel petal (LGB) and wing petal (YB) than in the flag petal (QB), and similarly, during the four periods of different petal types, the Cy3G content was higher in the initial flowering stage (S2), the full bloom stage (S3), and the final flowering stage (S4) than the flower bud stage (S1), which was in accordance with the trend of the observed petal floral color phenotypic difference measurement correlation. This suggested that the Cy3G accumulation was the primary factor driving the distinct coloration of varying types of petals. These findings could contribute to the understanding of the biochemical mechanisms underlying S. japonica petal coloration and may support future efforts in flower color improvement. Full article

Colchicine and ⁶⁰Co-γ radiation are commonly used breeding techniques for kiwifruit, offering advantages such as low cost, rapid execution, and high efficiency. The buds of red-fleshed kiwifruit (Actinidia chinensis) cv. ‘Donghong’ were used as experimental material and subjected to different concentrations of colchicine and different doses of ⁶⁰Co-γ radiation, respectively. Then, the buds were grafted on rootstock, and the ploidy, leaf size, and fruit quality of mutant fruit were evaluated, and principal component analysis (PCA) and simple sequence repeat markers were used to comprehensively assess and detect genetic variations, respectively. The results indicated that a total of 19 buds successfully germinated, with 13 branches successfully bearing fruit. Significant changes were observed in both leaf and fruit morphology following the mutation treatments. Most of the mutant materials showed significant increases in fruit weight, flesh firmness, and soluble sugar content, while titratable acidity and ascorbic acid content significantly decreased. Notably, the 25Gy ⁶⁰Co-γ radiation (25d) treatment demonstrated outstanding results, with fruit weight increasing by 256.10%, soluble sugar content rising by 88.29%, titratable acidity decreasing by 29.86%, and ascorbic acid content increasing by 35.60%. PCA results showed that the 25d mutant had the best comprehensive traits. And, except for the 0.4c mutant, all other mutant materials exhibited significant genetic changes at the DNA level. Full article

Albino mutation is among the most common phenomena that often causes a water imbalance and disturbs physiological functions in higher species of trees. Albinism frequently occurs in hybridized apples, but almost all seedlings die shortly after germination. In this study, a spontaneous albino mutant on Fuji apple trees was obtained. After bud grafting, new albino shoots with greenish-white leaves grew, although they were slender, small, and died easily. Resequencing analysis indicated that a total of 49.37 Gbp clean data of the albino mutant samples was obtained; its Q30 reached 91.43%, the average rate mapped was 93.69%, and genome coverage was 96.47% (at least one base cover). Comparisons of the sequences for the albino mutants revealed 4,817,412 single-nucleotide polymorphisms (SNPs), 721,688 insertion/deletion markers (InDels), and 43,072 structural variations (SVs). The genes with non-synonymous SNPs, InDels, and SVs in CDS were compared with KEGG, GO, COG, NR, and SwissProt databases, and a total of 5700 variant genes were identified. A total of 1377 mutant genes had the GO annotation information. Among these, 1520 mutant genes had the pathway annotation and took part in 123 pathways. A total of 1935 variant genes were functionally classified into 25 COG categories. Further research on these variants could help understand the molecular regulatory mechanism of the apple albino mutant. Similarly, variations in the homologous MdAPG1 (Albino or pale-green mutant 1) gene, which was located on Chromosome 11 and belonged to the S-adenosyl-L-methionine-dependent methyltransferases superfamily, may have led to the generation of this apple albino mutant. Full article

The global burden of respiratory syncytial virus (RSV) and severe associated disease is prodigious. RSV-specific vaccines have been launched recently but there is no antiviral medicine commercially available. RSV polymerase (L) protein is one of the promising antiviral targets, along with fusion and nucleocapsid proteins. During medicinal chemistry campaigns, two potent L-protein inhibitors (PC786 and PC751) were identified. Both compounds inhibited the RSV A/B-induced cytopathic effect in HEp-2 cells equally, but PC786 was more potent than PC751 in bronchial epithelial cells. Repeated treatment with escalating concentrations on RSV A2-infected HEp-2 cells revealed both inhibitors led to a Y1631H mutation in the L protein, but only PC786 induced a mutation in the M protein (V153A). By L protein fragment and M protein binding analysis, we showed that the M protein interacts with the 1392–1735 amino acid region of the L protein, where PC786 potentially binds. In addition, PC786 treatment or PC786-induced mutant RSV was found to increase M-protein nuclear localisation later in infection, concomitant with delayed fusion protein localisation at the budding viral filaments. As M protein is known to play a key role in virus assembly and budding late in infection, our data suggests that disrupting the interaction between the M and L proteins could provide a novel target for antiviral development. Full article

Heading date 3a (Hd3a, a FLOWERING LOCUS T (FT) ortholog from rice) is well known for its important role in rice (Oryza sativa L.), controlling floral transition under short-day (SD) conditions. Although the effect of Hd3a on promoting branching has been found, the underlying mechanism remains largely unknown. In this report, we overexpressed an Hd3a and BirAG (encoding a biotin ligase) fusion gene in rice, and found that early flowering and tiller bud outgrowth was promoted in BHd3aOE transgenic plants. On the contrary, knockout of Hd3a delayed flowering and tiller bud outgrowth. By using the BioID method, we identified multiple Hd3a proximal proteins. Among them, D14, D53, TPR1, TPR2, and TPRs are central components of the strigolactone signaling pathway, which has an inhibitory effect on rice tillering. The interaction between Hd3a, on the one hand, and D14 and D53 was further confirmed by the bimolecular fluorescence complementation (BiFC), yeast two-hybrid (Y2H), and co-immunoprecipitation (Co-IP) methods. We also found that Hd3a prevented the degradation of D53 induced by rac-GR24 (a strigolactone analog) in rice protoplasts. RT-qPCR assay showed that the expression levels of genes involved in strigolactone biosynthesis and signal transduction were altered significantly between WT and Hd3a overexpression (Hd3aOE) or mutant (hd3a) plants. OsFC1, a downstream target of the strigolactone signaling transduction pathway in controlling rice tillering, was downregulated significantly in Hd3aOE plants, whereas it was upregulated in hd3a lines. Collectively, these results indicate that Hd3a promotes tiller bud outgrowth in rice by attenuating the negative effect of strigolactone signaling on tillering and highlight a novel molecular network regulating rice tiller outgrowth by Hd3a. Full article

Glycoside hydrolases (GHs), enzymes that break down glycosidic bonds in carbohydrates and between carbohydrates and non-carbohydrates, are prevalent in plants, animals, microorganisms, and other organisms. The tomato is a significant crop that contains the GH17 gene family. However, its role in tomatoes has yet to be fully investigated. In this study, we identified 43 GH17 genes from the tomato genome, distributed unevenly across 12 chromosomes. We further analyzed their gene structure, phylogenetic relationships, promoter elements, and expression patterns. The promoter element analysis indicated their potential roles in response to biotic and abiotic stresses as well as phytohormone effects on growth and development. The expression studies across different tomato tissues revealed that 10 genes were specifically expressed in floral organs, with SlA6 prominently expressed early during bud formation. By using CRISPR/Cas9 gene-editing technology, SlA6 knockout plants were generated. Phenotypic characterization showed that pollen viability, pollen tube germination, fruit weight, and seed number were significantly reduced in the Sla6 mutant, but the soluble solids content (TSS) was significantly higher in the Sla6 mutant, suggesting that SlA6 affects pollen development and fruit quality. Full article

Multiple transcription factors in the budding yeast Saccharomyces cerevisiae are required for the switch from fermentative growth to respiratory growth. The Hap2/3/4/5 complex is a transcriptional activator that binds to CCAAT sequence elements in the promoters of many genes involved in the tricarboxylic acid cycle and oxidative phosphorylation and activates gene expression. Adr1 and Cat8 are required to activate the expression of genes involved in the glyoxylate cycle, gluconeogenesis, and utilization of nonfermentable carbon sources. Here, we characterize the regulation and function of the zinc cluster transcription factor Gsm1 using Western blotting and lacZ reporter-gene analysis. GSM1 is subject to glucose repression, and it requires a CCAAT sequence element for Hap2/3/4/5-dependent expression under glucose-derepression conditions. Genome-wide CHIP analyses revealed many potential targets. We analyzed 29 of them and found that FBP1, LPX1, PCK1, SFC1, and YAT1 require both Gsm1 and Hap4 for optimal expression. FBP1, PCK1, SFC1, and YAT1 play important roles in gluconeogenesis and utilization of two-carbon compounds, and they are known to be regulated by Cat8. GSM1 overexpression in cat8Δ mutant cells increases the expression of these target genes and suppresses growth defects in cat8Δ mutants on lactate medium. We propose that Gsm1 and Cat8 have shared functions in gluconeogenesis and utilization of nonfermentable carbon sources and that Cat8 is the primary regulator. Full article

Chardonnay is one of the most popular white grape wine varieties in the world, but this wine lacks typical aroma, considered a sensory defect. Our research group identified a Chardonnay bud sport with typical muscat characteristics. The goal of this work was to discover the key candidate genes related to muscat characteristics in this Chardonnay bud sport to reveal the mechanism of muscat formation and guide molecular design breeding. To this end, HS−SPME−GC−MS and RNA−Seq were used to analyze volatile organic compounds and the differentially expressed genes in Chardonnay and its aromatic bud sport. Forty-nine volatiles were identified as potential biomarkers, which included mainly aldehydes and terpenes. Geraniol, linalool, and phenylacetaldehyde were identified as the main aroma components of the mutant. The GO, KEGG, GSEA, and correlation analysis revealed HMGR, TPS1, TPS2, TPS5, novel.939, and CYP450 as key genes for terpene synthesis. MAO1 and MAO2 were significantly downregulated, but there was an increased content of phenylacetaldehyde. These key candidate genes provide a reference for the development of functional markers for muscat varieties and also provide insight into the formation mechanism of muscat aroma. Full article

Bioethanol fermentation from lignocellulosic hydrolysates is negatively affected by the presence of acetic acid. The budding yeast S. cerevisiae adapts to acetic acid stress partly by activating the transcription factor, Haa1. Haa1 induces the expression of many genes, which are responsible for increased fitness in the presence of acetic acid. Here, we show that protein kinase A (PKA) is a negative regulator of Haa1-dependent gene expression under both basal and acetic acid stress conditions. Deletions of RAS2, encoding a positive regulator of PKA, and PDE2, encoding a negative regulator of PKA, lead to an increased and decreased expression of Haa1-regulated genes, respectively. Importantly, the deletion of HAA1 largely reverses the effects of ras2∆. Additionally, the expression of a dominant, hyperactive RAS2^A18V19 mutant allele also reduces the expression of Haa1-regulated genes. We found that both pde2Δ and RAS2^A18V19 reduce cell fitness in response to acetic acid stress, while ras2Δ increases cellular adaptation. There are three PKA catalytic subunits in yeast, encoded by TPK1, TPK2, and TPK3. We show that single mutations in TPK1 and TPK3 lead to the increased expression of Haa1-regulated genes, while tpk2Δ reduces their expression. Among tpk double mutations, tpk1Δ tpk3Δ greatly increases the expression of Haa1-regulated genes. We found that acetic acid stress in a tpk1Δ tpk3Δ double mutant induces a flocculation phenotype, which is reversed by haa1Δ. Our findings reveal PKA to be a negative regulator of the acetic acid stress response and may help engineer yeast strains with increased efficiency of bioethanol fermentation. Full article