Biology subjects

Jang, H. B.

Publications and source records attributed to Jang, H. B..

7 recordsLinked to original sources

bioRxiv2025

Scalable and systematic hierarchical virus taxonomy with vConTACT3

Viruses are key players in diverse ecosystems, but studying their impacts is technically and taxonomically challenging. Taxonomic complexities derive from undersampling, diverse DNA and RNA genomes with multiple evolutionary origins, and lack of a universal barcode gene. While virus ecogenomics has expanded access to and understanding of the virosphere, available classification tools poorly scale to modern discovery-based datasets, lack taxonomic resolution, and/or are unable to classify novel sequence space. Here we develop, benchmark, and release vConTACT3, a machine learning-based tool that improves scalability and accuracy, adds extensive user-requested features, expands classification to both eukaryote and prokaryote viruses for 4/6 officially recognized realms, and establishes accurate hierarchical taxonomy from genus to order. Application to 48,069 public virus genomes provided new taxonomy assignments for thousands of taxa, revealed support for fewer taxonomic ranks than currently available, and systematically identified taxonomically problematic areas across the virosphere.

bioinformatics↗

bioRxiv2025

Sub-daily Bermuda Atlantic Time Series virus sampling reveals taxonomy, host, and functional differences at the population, but not community level

Ocean microbes contribute to biogeochemical cycles and ecosystem function, but they do so under top-down pressure imposed by viruses. While viruses are increasingly understood spatially and beginning to be incorporated into predictive modeling, high-frequency ocean virus dynamics remain understudied due to methodological challenges. Here we sampled stratified Bermuda Atlantic Time Series (BATS) waters for 112 hours at sub-daily 4-(surface) or 12-(deep chlorophyll maximum) hour intervals, purified viral particles from these samples, sequenced their metagenomes, and used the resulting data to characterize high-frequency virus community dynamics. Aggregated community diversity metrics changed with depth, but were not statistically significant temporally at a fixed location. However, finer-scale population-level analyses revealed both depth and temporal change, including physicochemical depth-driven differences and, in surface waters, thousands of viral populations that exhibited statistically significant diel rhythms. Statistical analyses revealed three main archetypes of temporal dynamics that themselves differed in abundance patterns, host predictions, viral taxonomy, and gene functions. Among these, highlights include viruses resembling an archetype with a night peaking pattern in activity that include an over-representation of viruses that putatively infect Prochlorococcus, a phototrophic cyanobacteria. Together, these efforts provide baseline community-and population-scale short-time-frame observations relevant to future climate state modeling.

microbiology↗

bioRxiv2023

Population ecology and potential biogeochemical impacts of ssDNA and dsDNA soil viruses along a permafrost thaw gradient

Climate change is disproportionately warming northern peatlands, which may release large carbon stores via increased microbial activity. While there are many unknowns about such microbial responses, virus roles are especially poorly characterized with studies to date largely restricted to "bycatch" from bulk metagenomes. Here, we used optimized viral particle purification techniques on 20 samples along a highly contextualized peatland permafrost thaw gradient, extracted and sequenced viral particle DNA using two library kits to capture single-stranded (ssDNA) and double-stranded (dsDNA) virus genomes (40 total viromes), and explored their diversity and potential ecosystem impacts. Both kits recovered similar dsDNA virus numbers, but only one also captured thousands of ssDNA viruses. Combining these data, we explored population-level ecology using genomic representation from 9,560 viral operational taxonomic units (vOTUs); nearly a 4-fold expansion from permafrost-associated soils, and 97% of which were novel when compared against large datasets from soils, oceans, and the human gut. In silico predictions identified putative hosts for 44% (4,149 dsDNA + 17 ssDNA) of the identified vOTUs spanning 2 eukaryotic, 12 archaeal, and 30 bacterial phyla. The recovered vOTUs encoded 1,684 putative auxiliary metabolic genes (AMGs) and other metabolic genes carried by [~]10% of detected vOTUs, of which 46% were related to carbon processing and 644 were novel. These AMGs grouped into five functional categories and 11 subcategories, and nearly half (47%) of the AMGs were involved in carbon utilization. Of these, 112 vOTUs encoded 123 glycoside hydrolases spanning 15 types involved in the degradation of polysaccharides (e.g., cellulose) to monosaccharides (e.g., galactose), or further monosaccharide degradation, which suggests virus involvement in myriad metabolisms including fermentation and central carbon metabolism. These findings expand the scope of viral roles in microbial carbon processing and suggest viruses may be critical for understanding the fate of soil organic carbon in peatlands.

microbiology↗

bioRxiv2019

Integrative omics analysis of Pseudomonas aeruginosa virus PA5oct highlights the molecular complexity of jumbo phages

Pseudomonas virus vB_PaeM_PA5oct is a compelling model phage to investigate phage-bacteria interactions and is a potent candidate for phage therapy. Combining hybrid genome sequencing, RNA-Seq, and mass spectrometry of virion-associated proteins allowed us to accurately assemble and annotate PA5octs 286,783 bp genome. It encodes 461 coding regions, of which 93 were identified as virion-associated proteins using ESI-MS/MS. RNA-seq revealed twelve tRNA genes, four ncRNA regions, and a gradual take-over of the total cell transcriptome from 21% in early infection to 93% in late infection. Although PA5oct is not organized into strictly contiguous regions of temporal transcription, defined genomic regions are expressed in early, middle, and late phases of infection. Interestingly, we observed distinct regions showing limited transcription activity throughout the infection cycle. The infection of Pseudomonas aeruginosa by PA5oct triggers the upregulation of bacterial operons related to NAD biosynthesis, Psl exopolysaccharide, and periplasmic nitrate reductase production and downregulates Type IV pili gene products, suggesting mechanisms of superinfection exclusion. We used the proteome of PA5oct to position this isolate amongst other phages using a protein-sharing network. This study expands our understanding of the molecular diversity of jumbo viruses and opens new questions towards cellular regulation and phage-encoded hijacking mechanisms.

molecular biology↗

bioRxiv2019

Gene sharing networks to automate genome-based prokaryotic viral taxonomy

Viruses of bacteria and archaea are likely to be critical to all natural, engineered and human ecosystems, and yet their study is hampered by the lack of a universal or scalable taxonomic framework. Here, we introduce vConTACT 2.0, a network-based application to establish prokaryotic virus taxonomy that scales to thousands of uncultivated virus genomes, and integrates confidence scores for all taxonomic predictions. Performance tests using vConTACT 2.0 demonstrate near-identical correspondence to the current official viral taxonomy (>85% genus-rank assignments at 96% accuracy) through an integrated distance-based hierarchical clustering approach. Beyond "known viruses", we used vConTACT 2.0 to automatically assign 1,364 previously unclassified reference viruses to tentative taxa, and scaled it to modern metagenomic datasets for which the reference network was robust to adding 16,000 viral contigs. Together these efforts provide a systematic reference network and an accurate, scalable taxonomic analysis tool that is critically needed for the research community.

bioinformatics↗

bioRxiv2018

Genomic, transcriptomic, and structural analysis of Pseudomonas virus PA5oct highlights the molecular complexity among Jumbo phages

Pseudomonas virus PA5oct has a large, linear, double-stranded DNA genome (287,182 bp) and is related to Escherichia phages 121Q/PBECO 4, Klebsiella phage vB_KleM-RaK2, Klebsiella phage K64-1, and Cronobacter phage vB_CsaM_GAP32. A protein-sharing network analysis highlights the conserved core genes within this clade. Combining genome, RNAseq and mass spectrometry analyses of its virion proteins allowed us to accurately identify genes and elucidate regulatory elements for this phage (ncRNAs, tRNAs and promoter elements). In total PA5oct encodes 462 CDS (compared to 345 in silico predicted genes using automated annotation pipelines), of which 25.32%, have been identified as virion-associated based on ESI-MS/MS. The RNAseq-based temporal genome organization suggests a gradual take-over by viral transcripts from 21%, 69%, and 92% at 5, 15 and 25 min after infection, respectively. Like many large phages, PA5oct is not organized into contiguous regions of temporal transcription. However, although the temporal regulation of the PA5oct genome expression reveals specific genome clusters expressed in early and late infection, many genes encoding experimentally observed structural proteins surprisingly appear to remain almost untranscribed throughout the infection cycle. Within the host, operons associated with elements of a cryptic Pf1-like prophage are upregulated, as are operons responsible for Psl exopolysaccharide (pslE-J) and periplasmic nitrate reductase (napA-F) production. The characterization described here represents a crucial step towards understanding the genomic complexity as well as molecular diversity of jumbo viruses.

genomics↗

bioRxiv2018

Soil viruses are underexplored players in ecosystem carbon processing

Rapidly thawing permafrost harbors ~30-50% of global soil carbon, and the fate of this carbon remains unknown. Microorganisms will play a central role in its fate, and their viruses could modulate that impact via induced mortality and metabolic controls. Because of the challenges of recovering viruses from soils, little is known about soil viruses or their role(s) in microbial biogeochemical cycling. Here, we describe 53 viral populations (vOTUs) recovered from seven quantitatively-derived (i.e. not multiple-displacement-amplified) viral-particle metagenomes (viromes) along a permafrost thaw gradient. Only 15% of these vOTUs had genetic similarity to publicly available viruses in the RefSeq database, and ~30% of the genes could be annotated, supporting the concept of soils as reservoirs of substantial undescribed viral genetic diversity. The vOTUs exhibited distinct ecology, with dramatically different distributions along the thaw gradient habitats, and a shift from soil-virus-like assemblages in the dry palsas to aquatic-virus-like in the inundated fen. Seventeen vOTUs were linked to microbial hosts (in silico), implicating viruses in infecting abundant microbial lineages from Acidobacteria, Verrucomicrobia, and Deltaproteoacteria, including those encoding key biogeochemical functions such as organic matter degradation. Thirty-one auxiliary metabolic genes (AMGs) were identified, and suggested viral-mediated modulation of central carbon metabolism, soil organic matter degradation, polysaccharide-binding, and regulation of sporulation. Together these findings suggest that these soil viruses have distinct ecology, impact host-mediated biogeochemistry, and likely impact ecosystem function in the rapidly changing Arctic.

microbiology↗