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    2026 International SPP 2330 Symposium Berlin

    5–7 Oct 2026
    Harnack-Haus
    Europe/Berlin timezone

    Contact/Support: SPP 2330

    Function of Phage Transfer-Messenger RNA in a crAss-like phage phi14:2

    5 Oct 2026, 15:20
    15m
    Goethe-Saal (Harnack-Haus)

    Goethe-Saal

    Harnack-Haus
    Short-talk only Cellular organisation and regulation of the viral infection cycle Organisation and regulation of the viral infection cycle

    Speaker

    Nandika Sanjog Sahani (Max Planck Institute of Biochemistry)

    Description

    CrAss-like phages are a group of viruses that include some of the most abundant phages in the human gut. These phages infect bacteria of the Bacteroidetes phylum. Despite their abundance, their molecular biology remains poorly understood.

    In this study, we use phi14:2, a crAss-like phage isolated from the marine microbiome that infects Cellulophaga baltica, as a model system to investigate the role of phage-encoded transfer-messenger RNA (tmRNA). In bacteria, tmRNA rescues stalled ribosomes from defective mRNA transcripts lacking a stop codon and directs incomplete proteins for degradation through a process known as trans-translation. The role of phage tmRNA remains unknown.

    We show that the phage tmRNA is one of the most abundant transcripts produced during infection. The entire pool of phage tmRNA co-fractionates with host ribosomes and interacts with host SmpB, a protein required for tmRNA activity. We demonstrated that the phage tmRNA-encoded tag peptide is a degradation tag, promoting more efficient degradation than the host one. To reveal the function of the phage tmRNA, we established a reporter system in C. baltica to monitor trans-translation.

    In parallel, we established in-cell crosslinking mass spectrometry for phage-infected bacteria, enabling detection of phage-host protein interactions. We identified phage protein gp40 interacting with host RNase R, an enzyme responsible for degrading non-stop transcripts in coordination with trans-translation. This suggests that the phage may contribute to the disposal of non-stop transcripts.

    Reference #2

    Janssen, B.D., Hayes, C.S. The tmRNA ribosome-rescue system. Advances in Protein Chemistry and Structural Biology 86, 151–191 (2012).

    Reference #1

    Drobysheva, A.V., Panafidina, S.A., Kolesnik, M.V. et al. Structure and function of virion RNA polymerase of a crAss-like phage. Nature 589, 306–309 (2021).

    Reference #3

    O'Reilly, F.J., Graziadei, A., Forbrig, C. et al. Protein complexes in cells by AI-assisted structural proteomics. Mol. Syst. Biol. 19, e11544 (2023).

    Author

    Nandika Sanjog Sahani (Max Planck Institute of Biochemistry)

    Co-authors

    Ms Elizaveta Buianova (Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany) Mr Baturay Altay (Max Planck Institute of Biochemistry) Mr Huanzhang Tang (Max Planck Institute of Biochemistry) Dr Barbara Steigenberger (Max Planck Institute of Biochemistry) Mr Mikhail Fofanov (Friedrich Schiller University, Jena, Germany) Dr Cedric Lood (Friedrich Schiller University, Jena, Germany) Dr Milan Gerovac (Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany, Helmholtz Centre for Infection Research, Braunschweig, Germany) Prof. Bas Dutilh (Friedrich Schiller University, Jena, Germany) Prof. Jörg Vogel (Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany) Dr Maria Sokolova (Max Planck Institute of Biochemistry)

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