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A new family of bacterial ribosome hibernation factors.

ABSTRACT: To conserve energy during starvation and stress, many organisms use hibernation factor proteins to inhibit protein synthesis and protect their ribosomes from damage^1,2. In bacteria, two families of hibernation factors have been described, but the low conservation of these proteins and the huge diversity of species, habitats and environmental stressors have confounded their discovery^3-6. Here, by combining cryogenic electron microscopy, genetics and biochemistry, we identify Balon, a new hibernation factor in the cold-adapted bacterium Psychrobacter urativorans. We show that Balon is a distant homologue of the archaeo-eukaryotic translation factor aeRF1 and is found in 20% of representative bacteria. During cold shock or stationary phase, Balon occupies the ribosomal A site in both vacant and actively translating ribosomes in complex with EF-Tu, highlighting an unexpected role for EF-Tu in the cellular stress response. Unlike typical A-site substrates, Balon binds to ribosomes in an mRNA-independent manner, initiating a new mode of ribosome hibernation that can commence while ribosomes are still engaged in protein synthesis. Our work suggests that Balon-EF-Tu-regulated ribosome hibernation is a ubiquitous bacterial stress-response mechanism, and we demonstrate that putative Balon homologues in Mycobacteria bind to ribosomes in a similar fashion. This finding calls for a revision of the current model of ribosome hibernation inferred from common model organisms and holds numerous implications for how we understand and study ribosome hibernation.

SUBMITTER: Helena-Bueno K

PROVIDER: S-EPMC10901736 | biostudies-literature | 2024 Feb

REPOSITORIES: biostudies-literature

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A new family of bacterial ribosome hibernation factors.

Helena-Bueno Karla K Rybak Mariia Yu MY Ekemezie Chinenye L CL Sullivan Rudi R Brown Charlotte R CR Dingwall Charlotte C Baslé Arnaud A Schneider Claudia C Connolly James P R JPR Blaza James N JN Csörgő Bálint B Moynihan Patrick J PJ Gagnon Matthieu G MG Hill Chris H CH Melnikov Sergey V SV

Nature 20240214 8001

To conserve energy during starvation and stress, many organisms use hibernation factor proteins to inhibit protein synthesis and protect their ribosomes from damage<sup>1,2</sup>. In bacteria, two families of hibernation factors have been described, but the low conservation of these proteins and the huge diversity of species, habitats and environmental stressors have confounded their discovery<sup>3-6</sup>. Here, by combining cryogenic electron microscopy, genetics and biochemistry, we identify ...[more]

PMID: 38355796

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A new family of bacterial ribosome hibernation factors.

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A new family of bacterial ribosome hibernation factors.

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