Search Results (1,021)

Simple recursive rules often conceal surprisingly complex structures, and the Tribonacci sequence is an interesting example of how elementary arithmetic can lead to complex and visually expressive patterns. In this research paper, we present triangular arrays generated by a Petri net encoding of the Tribonacci recurrence, extending our previous Fibonacci construction. Token propagation realizes the delayed dependencies of the recurrence and gives rise to a directed global triangular geometry. Parity and modular colourings highlight persistent self-similar motifs reminiscent of classical fractal patterns. We also outline higher-order k-bonacci extensions and compare the resulting visual structures. Within this framework, global fractal-like visibility tends to degrade as the order increases, while extreme orders can enter a different limiting regime. Full article

The 5′-proximal region of the citrus tristeza virus (CTV) RNA genome is a hub where several elements involved in different facets of the virus cycle reside, including the sequences driving the production of the viral long non-coding RNA (lncRNA) LMT1. The sequence of this region is one of the most divergent genome areas, allowing for strain differentiation. Beyond its use in assessing viral population diversity, the region provides a valuable model for studying the conservation of RNA structure and function despite sequence variation. Here, we integrated comparative in silico analysis of the LMT1 region from variants of eight CTV strains with selective 2′-hydroxyl acylation, analyzed by primer extension and mutational profiling (SHAPE-MaP) probing of in vitro–generated LMT1 RNAs from two divergent strains, T36 and T68. The predicted consensus structures revealed 19 putative, conserved stem-loops. The SHAPE-MaP reactivity data supported and substantiated the thermodynamics-based predictions for the 15 previously uncharacterized stem-loops and two functional elements identified earlier. The strong structural conservation across strains highlights that the LMT1 RNA structure contributes to its function during CTV infection. These results provide the first experimentally supported structure of this viral lncRNA and lay the foundation for defining how individual RNA motifs influence CTV biology. Full article

S. suis is a major zoonotic infectious disease whose serological diversity brings challenges to vaccine development. Based on the whole-genome data of 169 S. suis strains, this study conducted a systematic bioinformatics analysis of the surface antigen protein HP0197 that reveals its distribution characteristics, sequence diversity, domain composition and antigenic epitope distribution. The results showed that the HP0197 gene, which has a detection rate of 91.72%, can be divided into seven major phylogroups (I–VII) and the following two structural types: short form (HP0197-S) and long form (HP0197-L). All sequences contained signal peptides, transmembrane structures, LPXTG anchoring motifs, as well as conserved GAGBD and G5 domains, among which tandem repeats of the G5 domain existed in the long HP0197-L type. Tertiary structure prediction indicated that HP0197 has a spatial architecture of “conserved at both ends and flexible in the middle”, in which B-cell epitopes are mainly enriched near the GAGBD and G5 domains, suggesting these regions are the key targets for inducing cross-immune protection. It systematically elucidates the diversity and structural characteristics of the HP0197 protein from the perspective of population genetics, which provides a theoretical basis for optimizing existing subunit vaccines, designing broad-spectrum multi-epitope vaccines and exploring novel anti-infection strategies. Full article

Alternaria brown spot, caused by the tangerine pathotype of Alternaria alternata, is a destructive fungal disease affecting citrus production worldwide. Nucleotide-binding site-leucine-rich repeat (NBS-LRR) genes constitute a major class of plant immune receptors; however, their genome-wide characteristics and potential association with Alternaria brown spot resistance loci in citrus remain poorly understood. In this study, we performed a comprehensive genome-wide identification and comparative analysis of NBS-LRR genes across representative citrus species. A total of 417 and 326 NBS-LRR genes were identified in Citrus reticulata and Citrus clementina, respectively, and were classified into NL, CNL, TNL, and RNL subfamilies based on domain architecture. Phylogenetic reconstruction, gene structure analysis, conserved motif composition, chromosomal distribution, synteny relationships, and promoter cis-element profiling collectively revealed considerable structural variation and lineage-specific expansion of the NBS-LRR gene family in citrus genomes. By integrating previously reported quantitative trait locus (QTL) data for Alternaria brown spot, we identified several NBS-LRR genes located within a resistance-associated genomic interval on chromosome 3. Among these, a candidate gene, designated LRR2, exhibited differential transcriptional responses upon pathogen inoculation and displayed distinct sequence variations between citrus genotypes. Structural modeling and molecular docking analyses suggested potential binding interfaces between LRR2 and multiple host-selective toxins, although the biological relevance of these interactions requires further experimental validation. Subcellular localization assays in Nicotiana benthamiana showed that LRR2 is distributed in both the nucleus and cytoplasm. Notably, transient overexpression of LRR2 triggered hypersensitive response-like cell death and H₂O₂ accumulation. Collectively, this study provides a comprehensive overview of the citrus NBS-LRR gene family and presents a multifaceted characterization of a QTL-anchored candidate gene. These findings establish a genomic and molecular framework for further functional investigations of citrus–Alternaria interactions. Full article

Seasonal human coronaviruses (HCoVs) continue to undergo adaptive evolution under structural and immune-mediated constraints. We investigated the molecular epidemiology and spike (S) protein structural variation of circulating coronaviruses in Riyadh, Saudi Arabia, during the 2025–2026 winter season, with particular emphasis on genotype persistence and glycosylation architecture in HCoV-OC43. Among 293 nasopharyngeal aspirates (NPAs) collected from hospitalized patients with acute respiratory illness, HCoV-OC43 was detected in 26 cases (8.87%), whereas other seasonal coronaviruses were not identified. Partial sequencing of the S gene revealed 97.84–98.23% nucleotide identity relative to the prototype strain VR-759, with amino acid substitutions distributed at discrete positions rather than within extended variable domains, indicating structural conservation. Phylogenetic reconstruction demonstrated that all Riyadh isolates clustered within genotype C, together with previously circulating local strains, supporting sustained endemic persistence and in situ evolution. In silico analysis of the S protein glycosylation landscape identified four invariant N-linked glycosylation motifs (N-X-S/T) at residues 46, 121, 134, and 190, reflecting strong structural constraints on glycan-dependent folding and antigenic configuration. A genotype-associated K68N substitution generated an additional N-glycosylation motif (68NGTD) in multiple Riyadh isolates, potentially modifying local glycan shielding without disrupting the overall glycosylation framework. The preservation of core glycosylation sites alongside selective motif acquisition suggests evolutionary fine-tuning of S surface topology rather than large-scale structural remodeling. Collectively, these findings indicate that genotype C persistence in Riyadh is accompanied by conserved S architecture and subtle glycosylation adjustments that may modulate immune recognition while maintaining structural integrity. Continued high-resolution molecular surveillance will be critical for defining the functional consequences of S microevolution in endemic HCoVs. Full article

MYO16 has previously been identified as a candidate gene in studies of meat productivity in sheep, but its complete sequence and the potential impact of polymorphisms on the functional properties of the gene in sheep remain understudied. The aim of this study was to analyze genetic variation in the MYO16 gene region in sheep and to identify polymorphisms that, according to bioinformatic prediction, are capable of changing the amino acid sequence of the protein or are associated with allele-specific differences in transcription factor binding motifs potentially significant for gene regulation or protein structure. Whole-genome sequencing was performed for genomic DNA from Manych Merino rams (n = 30) on an Illumina NovaSeq 6000 platform. Variants within the MYO16 region were extracted and annotated. For each variant, ±30 bp reference and alternative sequences were scanned with FIMO using the JASPAR 2020 Vertebrates PWMs to detect allele-specific gain or loss of significant motif hits. TFLink (Mus musculus) was used to retain only TFs with MYO16 listed as a target. In the MYO16 gene region, 10,318 variants were detected. The coding region contained 54 SNPs, including 15 missense variants. In silico TFBS scanning identified 23 variants showing allele-specific gain or loss of significant motif hits, involving motifs for EBF1, CTCF, NRF1, SPI1, NFE2L2, JUN, and GFI1. We examined polymorphism in the ovine MYO16 gene region and identified candidate variants to be tested for association with productivity traits in future genotype–phenotype studies. Full article

Intestinal infections caused by Salmonella enterica serovar Typhi (S. Typhi) remain a global health concern, making preventive strategies and diagnostic tools essential. This study aimed to identify mimotope peptides of the Vi antigen using phage display and assess their recognition by rabbit and 46 human sera, as well as their potential for diagnosis and immunogen design. Rabbits were immunized with the Vi antigen (AgVi) from S. Typhi ATCC 6539, and sera-derived IgG was used for phage biopanning. DNA sequences from selected phagotopes were synthesized as Salmonella mimotope peptides (SMPs), either linear or KLH-conjugated. Their reactivity was tested with ELISAs against AgVi and SMPs, using both rabbit sera and 46 human serum samples. Ten phagotopes were identified, with a consensus motif (D/G–A/V–x–P–x–x–G–x–x–x–x–x), suggesting α-helix structures. Immunization with KLH-conjugated peptides generated specific antibodies, particularly SMPVi/5 and SMPVi/10, which recognized AgVi and their respective peptides. Competitive inhibition assays confirmed that SMPVi/5 reduced the anti-AgVi binding in a dose-dependent manner. In human sera, AgVi recognition occurred in 52% of samples, while SMPVi/5 and SMPVi/10 were recognized in 45%. Overall, SMPVi/5 demonstrated immunogenicity and functional mimicry, supporting its use as a synthetic reagent for serological assays and as a candidate for immunogen design. Full article

Background/Objectives: Peroxiredoxins (Prxs) are key antioxidant enzymes involved in cellular redox homeostasis. Prx6 is a multifunctional member of the Prx family that has been reported in other organisms to possess glutathione peroxidase and phospholipase A₂ (PLA₂)-related activities. However, the structural and immunological roles of 1-Cys Prx6 in crustaceans remain poorly understood. This study aimed to identify and characterize a Prx6 gene from Penaeus vannamei (PvPrx6) and to evaluate its potential involvement in antioxidant defense. Methods: PvPrx6 cDNA was identified and analyzed using bioinformatics and AlphaFold2 modeling. Tissue distribution and transcriptional responses to lipopolysaccharide (LPS), poly(I:C), and peptidoglycan (PGN) were examined by RT-qPCR. Recombinant PvPrx6 (rPvPrx6) was expressed in Escherichia coli, and its antioxidant activity was evaluated in vitro using a metal-catalyzed oxidation (MCO) assay. Results: PvPrx6 encodes a 219-amino-acid protein containing conserved AhpC/TSA and 1-Cys Prx domains. Sequence comparison and 3D modeling revealed conserved peroxidase (Thr⁴¹, Cys⁴⁴, Arg¹²⁷) and residues (His²³, Lys²⁹, Asp¹³⁵) corresponding to the reported PLA₂-associated motif. Structural analysis suggested that Lys²⁹ occupies a position corresponding to the Ser³² residue of human Prx6, although this did not imply functional equivalence. PvPrx6 transcripts were highly expressed in the lymphoid organ and hepatopancreas and were significantly induced at 12 h following immune challenge. rPvPrx6 exhibited dose-dependent protection against hydroxyl radical-mediated DNA damage under the experimental conditions. Conclusions: Collectively, these findings suggest that PvPrx6 retains conserved structural characteristics of Prx6 proteins and may contribute to antioxidant defense in P. vannamei. However, further studies are required to validate its enzymatic activity and in vivo functional roles. Full article

Background: Chlorophyll degradation is a characteristic sign of fruit ripening. However, the chlorophyll degradation pathway during pitaya fruit development remains unexplored. Methods and Results: Here, chlorophyll contents showed a downward trend across the five developmental stages of ‘Jindu No.1’ pitaya peels. Based on the pitaya genome data, twenty chlorophyll degradation genes were identified, including two NYCs, three CLHs, five SGRs, six PAOs, and four RCCRs, spread across eight pitaya chromosomes. In addition, their phylogenetic relationships, conserved motifs, and domains were analyzed using homologous genes from beet and Arabidopsis species. Transcriptomic data and RT-qPCR analyses of these genes suggested that three HuSGRs demonstrated a significant upward trend during pitaya peel maturation. Indeed, the HuSGR1 has the complete gene structure, including the chloroplast transit peptide, SGR domain, and variable C-terminal region. However, HuSGR2 and HuSGR3 contained the N- and C-terminal sequences, respectively, of HuSGR1. They were separated by a 690 bp distance on chromosome 8, forming a gene cluster. Overexpressed HuSGR2 or HuSGR3 alone resulted in a significant decrease in chlorophyll contents in tobacco leaves. Notably, a more obvious reduction of chlorophyll contents was observed when overexpressing them together. Conclusions: Our results show that HuSGR2 and HuSGR3 were involved in accelerating the chlorophyll degradation process, providing new insights into the molecular basis of color formation in pitaya peels. Full article

Functional amyloids are widely distributed in bacteria and play important roles in biofilm formation and microbial physiology. However, most currently known bacterial amyloids have been identified through sequence homology to a limited number of prototype proteins, such as the curli subunit CsgA of Escherichia coli. This approach may overlook amyloidogenic sequences that lack recognizable similarity to these canonical systems. In this study, a cross-species, motif-based computational strategy was used to explore whether conserved sequence features derived from mammalian serum amyloid A (SAA) proteins could provide clues for identifying potential amyloidogenic motifs in bacterial proteomes. Comparative analysis of mammalian SAA isoforms identified a conserved sequence segment with predicted aggregation propensity, within which the hydrophobic motif SIAIILCILIL was observed in murine SAA3. Database searches revealed that similar sequence motifs occur in several proteins encoded by Gram-positive bacteria, including multiple proteins in Clostridioides difficile. To further explore whether C. difficile produces extracellular structures capable of interacting with amyloid-binding dyes, Congo Red-supplemented agar assays were performed. After 48 h of growth, both clinical isolates and a laboratory reference strain exhibited Congo Red-binding colony phenotypes. Because Congo Red binding can arise from several extracellular components and cannot be attributed to a specific protein or sequence motif, these observations should be interpreted cautiously. Taken together, this study presents a motif-based computational framework for identifying candidate amyloidogenic motifs across species and highlights sequence features in bacterial proteomes that may warrant further biochemical and structural investigation. The results should be regarded as hypothesis-generating and provide a basis for future experimental validation of potential amyloid-forming proteins in bacteria. Full article

Plant AT-rich sequence and zinc-binding (PLATZ) proteins are a class of plant-specific transcription factors that have been identified and functionally characterised in multiple species. However, the PLATZ gene family has not yet been systematically characterised in Populus euphratica. In this study, 19 PePLATZ genes were identified and classified into five subgroups. The analyses of gene structure, conserved motifs and protein domains indicated that the PLATZ family is highly conserved during evolution. Meanwhile, promoter cis-acting element profiling suggested their potential roles in stress-responsive transcriptional regulation. Transcriptomic and qRT-PCR analyses showed that PePLATZ1, PePLATZ6, PePLATZ8, PePLATZ14 and PePLATZ19 were highly expressed in the roots, stems and leaves of P. euphratica and were strongly induced by drought stress. PePLATZ8 localised to the nucleus and lacked transactivation activity but acted as a transcriptional repressor in planta. Transgenic poplar lines overexpressing PePLATZ8 exhibited significantly enhanced drought tolerance. Furthermore, after drought treatment, PePLATZ8-overexpressing plants accumulated high levels of H₂O₂ and exhibited significantly increased total superoxide dismutase activity, which likely contributed to improved drought tolerance. Together, the above findings deepen our understanding of the structure–function relationships of PePLATZ proteins and identify PePLATZ8 as a promising candidate gene for the molecular breeding of drought-resistant poplar germplasm. Full article

Background: Sulfate transporters (SULTRs) are integral membrane proteins responsible for sulfate uptake, translocation, and plant adaptation to abiotic stresses. However, knowledge regarding the SULTR gene family in the economically important crop, Brassica rapa (Chinese cabbage), limited. The aim of this study is to conduct a genome-wide identification and functional characterization of BrSULTR genes and to explore their potential functions under abiotic stress. Methods: We identified 19 BrSULTR genes in the B. rapa genome by performing homology searches with Arabidopsis thaliana SULTR sequences as queries. Subsequent bioinformatics analysis included phylogenetic classification, chromosomal localization, gene structure, conserved motif dissection, cis-regulatory element prediction, and protein–protein interaction (PPI) network analysis. Tissue-specific expression profiles of BrSULTRs were assessed using publicly available transcriptome data. Furthermore, their expression dynamics under salt (150 mM NaCl) and low-temperature (4 °C) stress were investigated by integrating transcriptomic, proteomic, and qRT-PCR data. Results: The 19 identified BrSULTR members were phylogenetically categorized into four subfamilies and were mapped unevenly across seven chromosomes. Promoter analysis identified an array of cis-regulatory elements associated with development, hormone response, and stress response. Expression profiles revealed distinct tissue-specific patterns in roots, stems, leaves, flowers, and siliques. Under salt stress, BrSULTR13 was significantly upregulated, while BrSULTR9 and BrSULTR11 were significantly suppressed under low-temperature stress. PPI network projection indicated that the Arabidopsis homologs of BrSULTR5 may physically interact with stress-regulating enzymes such as APS and APR. Conclusions: Our work presents a comprehensive genomic and functional overview of the BrSULTR gene family in B. rapa. The results underscore the potential functions of BrSULTRs, highlighting their involvement in sulfate transport and abiotic stress responses. These insights establish valuable insights and a foundation for further research aiming at improving stress tolerance in B. rapa through the manipulation of sulfur metabolism pathways. Full article

Adenosine triphosphate (ATP) serves as a central energy currency and signaling molecule in cellular processes, with ATP-binding sites in proteins playing critical roles in enzymatic catalysis, signal transduction, and gene regulation. The accurate identification of ATP-binding sites is essential for understanding protein function mechanisms and facilitating drug discovery, enzyme engineering, and disease pathway analysis. In this study, we present a novel hybrid deep learning framework that synergizes heterogeneous learning paradigms based on protein sequence information for accurate ATP-binding site prediction. Our approach integrates two complementary base classifiers. One is a Transformer-based model, which leverages high-level contextual embeddings generated by Evolutionary Scale Modeling 2 (ESM-2), a state-of-the-art protein language model, combined with a local–global dual-attention mechanism that enables the model to simultaneously characterize short-segment and long-range contextual dependencies across the entire protein sequence. The other is a deep Q-network (DQN)-inspired classifier that achieves residue-level prediction as a sequential decision-making process. The final predictions are generated using a weighted ensemble strategy, where optimal weights are determined via cross-validations to leverage the strengths of both models. The prediction results on benchmark independent testing sets indicate that our method achieves satisfactory performance on key metrics. Beyond predictive efficacy, this work uncovers the intrinsic biological mechanisms underlying protein–ATP interactions, including the synergistic roles of local structural motifs and global conformational constraints, as well as family-specific binding patterns, endowing the research with substantial biological significance. The research in this work offers a deeper understanding of the protein–ligand recognition mechanisms and supportive efforts on large-scale functional annotations that are critical for system biology and drug target discovery. Full article

The structural characterization of GG-rich DNA sequences in presence of metal ions provides essential insight into quadruplex stability and ion-dependent conformational specifics. We report the crystal structure of the GG-quadruplex formed by the sequence GGGGTTTTGGGG in the presence of Zn²⁺, K⁺, and Na⁺. It was deposited in the RCSB Protein Data Bank under the accession code 9FTA. The structure was determined by single-crystal X-ray diffraction at a resolution of 2.49 Å in the space group P2₁2₁2₁. It reveals a parallel-stranded, two-G-tetrad stabilized by K⁺ ions within the central channel, while Na⁺ and Zn²⁺ occupy peripheral and groove-associated sites. Zn²⁺ ions are engaged in noncanonical coordination interactions with phosphate oxygens and structured water molecules, contributing to lattice stabilization and subtle adjustments in groove dimensions. The T4 loop forms a compact, ordered motif that contributes to crystal packing rather than intramolecular G4 stabilization. The presence of mixed cations produces a sole lattice architecture mediated by ions that provides structural insight into how bivalent and monovalent metals mutually modulate G-quadruplex topology. These results suggest a basis for understanding the specific ion effects on G4 structures and may direct the design of metal open DNA architectures. Full article

Background/Objectives: The Arabidopsis thaliana GDS1 (Growth, Development and Splicing 1) gene has recently been identified as a key regulator linking nitrate signaling to leaf senescence. However, a systematic analysis of the GDS1 gene family in maize (Zea mays L.) is lacking. This study aims to identify and characterize the ZmGDS1 gene family in maize, providing a foundation for functional studies on their roles in growth, development, and low-nitrogen-induced leaf senescence. Methods: Putative ZmGDS1 family members were identified by searching the maize B73 reference genome using BLASTP (version 2.11.0+) and HMMER (version 3.4), with the Arabidopsis GDS1 protein sequence as the query. Candidate sequences were verified for the presence of the conserved zf-CCCH domain using NCBI CD-Search and SMART. Phylogenetic relationships, gene structures, conserved motifs, chromosomal distribution, collinearity, and promoter cis elements were comprehensively analyzed using MEGA 11, TBtools (version 1.098), MEME (version 5.5.9), and PlantCARE. Phylogenetic trees were constructed using the maximum likelihood (ML) method with the LG+G+I model and 1000 bootstrap replicates. Results: Thirteen ZmGDS1 genes were identified, distributed unevenly across eight maize chromosomes. Phylogenetic analysis classified the ZmGDS1 proteins into four distinct groups (A–D), revealing a lineage-specific expansion in group D. While all members contained the conserved zf-CCCH domain, their motif compositions varied considerably; ZmGDS1.1 exhibited the most complex structure, whereas ZmGDS1.12 had the most simplified. Subcellular localization predictions indicated that most ZmGDS1 proteins are targeted to the nucleus, consistent with a potential role as transcription factors. Promoter analysis revealed an abundance of cis elements associated with light response, hormone signaling (methyl jasmonate, abscisic acid, auxin), and stress responses. Notably, phylogenetically related genes tended to share similar cis-element profiles. Conclusions: This genome-wide analysis provides the first characterization of the ZmGDS1 gene family in maize. The observed structural conservation and diversity, together with regulatory elements linked to senescence-associated signals, support the hypothesis that ZmGDS1 genes may contribute to leaf senescence, particularly under low-nitrogen conditions. These findings provide a basis for future functional validation studies. Full article