biostudies-literatureUnknown16(1)Caviglia BProtein diffusion, critical for cellular metabolism, occurs in the highly crowded cytoplasm. Understanding how this dynamics changes when organisms are adapted to different thermal niches is a fundamental challenge in microbiology and biophysics. In Escherichia coli, protein diffusion undergoes a pronounced slowdown at temperatures near cellular death, coinciding with the early stages of unfolding. To determine whether this phenomenon is universal, we investigated psychrophilic and hyperthermophilic bacteria. In both species, a marked diffusion slowdown takes place at the onset of proteome melting. However, while the dynamic arrest is associated with the thermal death point for the hyperthermophilic proteome, the psychrophilic proteome maintains substantial mobility well beyond the cellulaNature communications10345https://www.ebi.ac.uk/biostudies/studies/S-EPMC12644737biostudies-literatureCytoplasmic fluidity and the cold life: proteome stability is decoupled from viability in psychrophiles.PMC12644737Paciaroni AGuiral MBeck CCaviglia BSterpone FSeydel TPeters JTimr SGiudici-Orticoni MTfalseCytoplasmic fluidity and the cold life: proteome stability is decoupled from viability in psychrophiles.Protein diffusion, critical for cellular metabolism, occurs in the highly crowded cytoplasm. Understanding how this dynamics changes when organisms are adapted to different thermal niches is a fundamental challenge in microbiology and biophysics. In Escherichia coli, protein diffusion undergoes a pronounced slowdown at temperatures near cellular death, coinciding with the early stages of unfolding. To determine whether this phenomenon is universal, we investigated psychrophilic and hyperthermophilic bacteria. In both species, a marked diffusion slowdown takes place at the onset of proteome melting. However, while the dynamic arrest is associated with the thermal death point for the hyperthermophilic proteome, the psychrophilic proteome maintains substantial mobility well beyond the cellula2025-01-01T00:00:00Z2025 Nov2026-06-05T19:01:57.499Z2026-05-20T03:14:38.937ZS-EPMC126447374128576810.1038/s41467-025-65270-5