Tominaga K. (tomiken)
@pacyc184.bsky.social
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Microorganisms and Viruses in the ocean https://sites.google.com/view/kentotominaga/
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pacyc184.bsky.social
Compositional analysis of bacterial peptidoglycan: insights from peptidoglycomics into structure and function | Journal of Bacteriology https://journals.asm.org/doi/full/10.1128/jb.00359-25?af=R
Compositional analysis of bacterial peptidoglycan: insights from peptidoglycomics into structure and function | Journal of Bacteriology
Peptidoglycan (PG) is a crucial biopolymer in the bacterial cell wall that has been the subject of intense study since it was first isolated in the early 1950s (1, 2). Over the last 70 years, extensive research has expanded our understanding of the structure and function of this microbial biopolymer. Recent advances in mass spectrometry and bioinformatics have revolutionized PG analysis, enabling a comprehensive detection of individual components and their global composition within bacterial cells. Like genomics, transcriptomics, and proteomics, peptidoglycomics is the non-targeted, non-biased detection of all elements that comprise the overall PG structure. Peptidoglycomic analyses can identify and monitor hundreds of potential compositional changes that occur within the PG structure of a cell. By comparison, traditional methods of analyzing PG composition only distinguish a relatively limited number of PG components. Therefore, peptidoglycomic approaches produce a detailed global overview of the PG structural elements and give unprecedented insight into the physiological function of this biopolymer within the bacterial cell.
journals.asm.org
pacyc184.bsky.social
Diel rhythms shape viral community structure and activity across the host domains of life | bioRxiv https://www.biorxiv.org/content/10.1101/2025.10.05.680483v1?rss=1
Diel rhythms shape viral community structure and activity across the host domains of life
Circadian rhythms, driven by endogenous clocks and synchronized with environmental cues, are fundamental to life on Earth. While extensively studied in diverse organisms, their influence on viral ecology remains largely unexplored. This study takes the temporal dynamics of viruses in Daya Bay as an example to uncover the rhythmic control of viral replication and activity. Using a high-resolution time-series dataset collected every 2 hours over a 3-day period, we identified a total of 22,151 viral operational taxonomic units (vOTUs) and 414 Nucleocytoplasmic Large DNA Virus (NCLDV) genomes. Our analysis revealed significant diel fluctuations, with 14.48% of vOTUs exhibiting diel patterns in metagenomic abundance and 1.97% showing diel transcriptional activity. We found that these abundant diel viruses infect hosts across the domains of life, including cyanobacteria, pelagibacteria, Marine Group II (MGII) archaea and protists, all known for their diel metabolism. The expanded spectrum of host diversity with diel viral interactions significantly broadens our understanding of virus-host rhythmic dynamics in natural environmental settings. A strong positive correlation was detected between the transcriptional activities of these diel viruses and their respective hosts. Contrary to bacteriophages, which mostly peaked during the day, we demonstrated that NCLDVs showed nocturnal diel abundance with a co-fluctuating diel transcriptomic activity pattern tightly hitched to their hosts, peaking at night and declining during the day. Furthermore, we identified a rich compendium of viral genes with significant diel expression patterns, including those related to structural protein production, DNA replication, and stress response. Notably, several essential viral genes involved in stress response and repair were found to be diel transcribed for the first time, including UV-endonuclease (UvdE), peroxidase, chaperones, and early light-induced protein (ELIP). Our findings suggest that viruses across host domains actively synchronize with environmental cues to optimize their replication and transmission, despite their dependence on host metabolism. This study provides novel insights into the rhythmic control of viral communities and their intricate interactions with hosts, with profound implications for microbial community succession and biogeochemical cycles. ### Competing Interest Statement The authors have declared no competing interest. National Natural Science Foundation of China, 2476109, 42276163, 42406144 the Shenzhen Science, Technology and Innovation Commission Program, JCYJ20220530115401003 SUSTech Education Reform Programme, SJZLGC202437 grant from the Deutsche Forschungsgemeinschaft, SPP 2330 project number 464976318
www.biorxiv.org
pacyc184.bsky.social
Single-cell Analysis of Attenuation-Driven Transcription Reveals New Principles of Bacterial Gene Regulation | bioRxiv https://www.biorxiv.org/content/10.1101/2025.10.06.680652v1?rss=1
Single-cell Analysis of Attenuation-Driven Transcription Reveals New Principles of Bacterial Gene Regulation
Transcription attenuation fine-tunes biosynthetic gene expression in bacteria via premature termination upon metabolic signals. In transcription initiation-controlled bacterial systems, promoter architecture and transcription factor binding sets the size of transcriptional bursts at σ70 promoters, while distal enhancer elements and associated transcriptional activators modulate burst frequency at σ54 promoters. Using the tryptophan biosynthesis operon as a model, we show that transcription attenuation, acting post-initiation and alongside transcriptional repression, simultaneously modulates both burst size and frequency from a σ70 promoter. This challenges the view that frequency modulation requires distal enhancer input and reveals that post-initiation mechanisms can shape divergent transcriptional bursting. We also uncover that bacteria use cross-feeding as a previously unrecognised strategy for controlling cell-to-cell variation in gene expression, with implications for metabolic coordination among cells. These findings redefine transcription dynamics within cell populations and suggest new principles by which bacteria regulate gene expression to adapt to environmental change. ### Competing Interest Statement The authors have declared no competing interest. Leverhulme Trust, RPG-2021-050 Biotechnology and Biological Sciences Research Council, BB/W019698/1
www.biorxiv.org